• Journal of the Institute of Electronics Engineers of Korea SP
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• v.37 no.6
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• pp.9-16
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• 2000

The perception of flicker on the computer display devices depends upon the temporal waveform of the phosphor decay characteristic, the frame rate, and the display size. The lowest frequency at which flicker is not perceived is called the critical fusion frequency or critical frequency. Critical fusion frequency is evaluated by the display illuminance and the modulation (m) defined as the ratio of the amplitude of first harmonic frequency to the DC of the waveform. In this paper, we analyze the relationship bet ween the critical fusion frequency, relating to the decay characteristic of the phosphors and luminance on the monitor, and the frame frequency. Also under considering the viewing angle, we presented the frame frequency that is less sensitive to the full size of the display device.

• Journal of Korean Society for Atmospheric Environment
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• v.30 no.2
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• pp.95-109
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• 2014

In this study, the concentration of odorants released from albumin (EA) and yolk (EY) portions of boiled egg samples were determined as a function of storage time. The concentrations were measured at storage days of 0, 1, 3, 6, and 9 under room temperature. As such, odorants produced during both fresh and decay conditions were measured through time. A total of 19 compounds were selected as the main target odorants along with 12 reference compounds. GC-MS (for VOC) and GC-PFPD system (for sulfur gases) equipped with thermal desorption (TD) system were employed for odorant analysis in this work. The initial concentrations measured from the chamber system were converted into flux terms ($ng{\cdot}g^{-1}{\cdot}min^{-1}$). The EA showed the highest concentration of $H_2S$ (234 $ng{\cdot}g^{-1}{\cdot}min^{-1}$) at EA-0, and the concentrations of AT (Acetone) was also seen clearly in the range of 11.7 (EA-0) to 58.6 $ng{\cdot}g^{-1}{\cdot}min^{-1}$ (EA-9). The EY showed similar patterns. EtAl (Ethyl alcohol) increased 9.47 (EA-1) to 96.7 $ng{\cdot}g^{-1}{\cdot}min^{-1}$ (EA-9) in EA samples. Ketone, alcohol, sulfur groups generally exhibited high concentrations compared to other odorants. These data were also compared in relation to olfactometry related dilution-to-threshold (D/T) ratio by air dilution sensory (ADS) test and sum of odor intensity (SOI).

• Korean Journal of Food Science and Technology
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• v.35 no.6
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• pp.1110-1116
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• 2003

The effects of packaging methods on the storage quality of minimally processed (prepeeled) onions were investigated to determine the optimal packing design. Various packaging treatments used for modifying headspace atmospheres included two passive MAP using LDPE and PP films, two active MAP using a gas mixture of 20% $O_2/10%\;CO_2/balance\;N_2$ and an ethylene scavenging sachet, and moderate vacuum packaging (MVP). The quality attributes of onion samples were evaluated periodically in terms of flesh weight loss, color of cut surface, decay ratio, microbial counts, and sensory properties during storage at $10^{\circ}C$ for 28 days. Packaging methods did not significantly influence surface color, weight loss, and microbiological populations of mesophiles, psychrotrophs, and lactic acid bacteria. They did, however, affect sensory characteristics as well as decay occurrence. Results indicated that seal-packaging with a gas-permeable plastic film under a mild vacuum condition could retain better onion quality in terms of microbial decay and visual sensory aspects as compared with the other packages.

• Food Science and Preservation
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• v.9 no.2
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• pp.126-130
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• 2002

Optimal storage conditions were investigated for 'Fuyu' persimmon fruits and cucumbers were stored under conditions of 70% relative humidity(RH) at 25$^{\circ}C$, 80% RH at l0$^{\circ}C$ and 90% at 5$^{\circ}C$ or l0$^{\circ}C$ of relative humidity, respectively and their qualities in microbial counts, decay ratio, surface color difference and chemical attributes were monitored during the storage period. 'Fuyu'persimmon fruits and cucumbers stored under 90% of relative humidity showed the minimal change in weight loss, decrease of ascorbic acid content, surface color difference and decay by putrefactive microorganisms. As the results of this experiment, 'Fuyu' persimmon fruits and cucumberf stored under 9% of relative humidity were best fer maintaining their freshness.

• Nuclear Engineering and Technology
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• v.25 no.1
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• pp.8-19
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• 1993

The natural convection model of the consolidated system has been developed to make sure the removal of decay heat generated in the spent fuel for the loss of forced cooling accident. The numerical technique employed was based on the ADI scheme. The calculation of heat generation rate in the spent fuel was peformed by the ANS-79 decay heat model, and the nonuniform surface heat flux is assumed with a chopped sine curve for the conservative decay heat generation input. The sensitivity study was performed to examine the possibility of the pool bulk boiling by varying the various parameters, i.e. inter-fuel spacing ratio, heat generation power, and radius of the fuel rod. The application results of this model show that the natural circulation flow through compacted spent fuel bundles enables the pool temperature to control in a safe and effective manner, after the required cooling time. The corresponding acceptance criteria of the cooling time for rearranging the spent fuel rods were also found.

• Food Science and Preservation
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• v.17 no.5
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• pp.581-585
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• 2010

The effects of plastic container vent ratio on fruit quality during strawberry precooling and storage were analyzed. Plastic containers ($520mm{\times}355mm{\times}182mm$) were manufactured with bottom and side vents at areal ratios of 5%, 10%, 15% and 20%. Fruit was loaded at a volume ratio of 80% prior to pressure cooling and storage at $5^{\circ}C$. The internal fruit temperature was $18^{\circ}C$ and the times taken to attain $2^{\circ}C$ after precooling were 1 hour 9 minutes, 1 hour 13 minutes, 2 hours 2 minutes, and 2 hours 51 minutes at vent ratios of 20%, 15%, 10%, and 5%, respectively. To mimic the current distribution system, precooled strawberries were packaged in tray wrapping and stored at $5^{\circ}C$. Changes in weight, bruising, extent of decay, and firmness, were measured. Weight loss, bruising, and decay were highest at a vent ratio of 20%, lowest at a vent ratio of 15%, and moderate at vent ratios of 5% and 10%. No significant among-treatment difference in fruit firmness was evident.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.5
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• pp.334-340
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• 2003

Exponential window function Is widely used In impact hammer testing to reduce leakage error as well as to get a good S/N ratio. The larger its decaying rate is, the more effectively the leakage errors are reduced. But if the decay rate of the exponential window is too large, the FRF is distorted. And the modal parameters of the system can not be exactly identified by modal analysis technique. Therefore, it is a difficult problem to determine proper decay rate in impact hammer testing. In this paper, amount of the FRF distortion caused by exponential window is theoretically uncovered. A new circle fitting method is also proposed so that the modal parameters are directly extracted from impulse response spectrum distorted by the exponential-windowed impulse response data. The results by the conventional and proposed circle fitting method are compared through a numerical example.

• Journal of Sensor Science and Technology
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• v.17 no.3
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• pp.217-222
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• 2008

$BaCl_2$ crystals were grown by using the Czochralski method, and their scintillation properties were measured. The emission spectrum was located in the range of $370{\sim}450$ nm, peaking at about 400 nm. The fluorescence decay time was approximately 75.9 ns for 662 keV ${\gamma}$-rays excitation. The energy resolution was about 24.4 % for $^{137}Cs$ 662 keV ${\gamma}$-rays, and the ${\alpha}/{\beta}$ ratio to $\alpha$ particles from a $^{210}Po$ 5.4 MeV was about 0.25.

• Journal of Biosystems Engineering
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• v.28 no.3
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• pp.261-268
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• 2003

Ten MHz pulsed NMR spectrometer was used to measure the magnetic resonance characteristics of Korean red ginseng. The difference in the internal structures of good and bad red ginsengs was examined by their NMR characteristics. Average values of $T_1$ and free induction decay(FID) ratios of under grade Korean red ginseng were the highest among the three groups categorized as normal, medium and under grades Korean red ginseng and average values of $T_2$ and $T_2$$^{＊}$ of them were the lowest among the three groups. Principal component analysis(PCA) was used to observe the contribution of measured NMR values to the grade of Korean red ginseng. The measured $T_1$, $T_2$, $T_2$$^{＊}$ and FID ratio of 79 Korean red ginsengs classified as normal grade, medium grade and under grade were examined using PCA analysis. Cumulative variance of PC1 through PC3 occupied more than 90% of total variance at first and second NMR measurement. Plots of PC scores for the most important PCs showed that normal red ginseng samples were distributed around the left region of PC1 axis and most of the undergrade red ginseng samples were scattered around the right region of PC1 axis.

• Food Science and Preservation
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• v.7 no.2
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• pp.145-149
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• 2000

Strawberry and cucumber were dipped with Korean medical herb extracts such as Rheum palmatum L. and Coptis chinensis Franch. to maintain the keeping quality during storage at 5$^{\circ}$C and 10$^{\circ}$C, respectively. Treatment with 500 ppm solutions gor strawberry retarded weight loss, microbial load increase, and decay during storage. Decay ratio was shown 68.8% for control, 45.0% for Rheum palmatum L. and 42.5% for Coptis chinensis Franch. at 10 days. Strawberry treated with Coptis chinensis Franch. showed a higher hardness and soluble solid content than others. Cucumber treated with 1,000 ppm solutions revealed a different O$_2$ and CO$_2$ concentrations after 16 days. Korean medical herb extracts showed an antimicrobial activity for the quality retention of cucumber during storage. Ascorbic acid content was generally increased till 8 days, but decreased thereafter.