• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.6
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• pp.367-372
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• 2009

The performance of a $CO_2$ heat pump water heater was measured with a variation of operating conditions such as refrigerant charge amount, outdoor temperature, compressor frequency, EEV opening, and water mass flow rate. The optimum refrigerant charge amount of the $CO_2$ system was 1800 g. At water mass flow rates of 75, 85, and 95 kg/h, the water heating temperatures were 74, 67, and $62^{\circ}C$ and COPs were 2.6, 2.8, and 3.0, respectively. Besides, the compressor frequency and water mass flow rate were adjusted to maintain the water heating temperature at $60^{\circ}C$ with the decrease of outdoor temperature. As the outdoor temperature decreased by $5^{\circ}C$, the compressor frequency increased beyond 60 Hz and the water mass flow rate decreased by 16.7%.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.4
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• pp.548-553
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• 2004

Patties were prepared using Barbari male goats meat (age about 4 yrs) and packed in HDPE under vacuum (VP) and aerobically (AP). Packed patties were stored at 4$\pm$1$^{\circ}C$ and evaluated for physico-chemical, microbiological and sensory changes on days 0, 5, 10, 15, 20 and 25. Overall mean water activity ($a_{w}$), moisture (%), fat (%), pH, TBA number and W-B shear force values (kg/$cm^{2}$) of patties were 0.983, 61.93, 18.39, 6.38, 0.150 and 0.86, respectively. Except pH that was significantly higher and TBA number significantly lower in VP patties, treatment had no significant (p>0.05) effect on other physico-chemical traits. However, storage period significantly (p<0.05) affected physico-chemical traits. Moisture (63.79%) and $a_{w}$ (0.985) were significantly (p<0.05) higher on day 25. Patties became firmer on day 20 onwards as indicated by higher W-B shear force. Though packaging method had no significant effect, storage period influenced microbial counts. The standard plate counts (SPC), which were initially log 5.98 CFU/g decreased significantly (p<0.05) on day 10 followed by steady increase and reaching log 4.89 on day 25. Almost similar trend was observed for psychrotrophic bacteria counts. Lactic acid bacteria counts declined as the storage period progressed. Coliforms, and yeast and mould counts were either not detected by the method used or were very low in numbers. All samples of AP patties revealed swollen, greasy and sticky surface with spongy texture on day 20 whereas only some of the VP patties shown such changes on day 20. Results indicated that vacuum packaging had definite advantage in preserving the sensory quality of patties than aerobic packaging but it did not help in extending the shelf-life beyond 15 days.

• Journal of Educational Research in Mathematics
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• v.18 no.2
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• pp.239-261
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• 2008

This study presents results by the content areas in mathematics. Average performance is provided for five content areas: number, algebra, measurement, geometry, and data. Relative achievement is shown among the content areas for 4 countries in comparison to Korea. In number, Korea had lower average achievement than Singapore, especially for ratio proportion percent. Among 5 countries, Korea had the highest average achievement in algebra and geometry, but the lowest in attributes and units of measurement. In data, Korean students didn't learn the followings successfully: a) comparing characteristics of data sets and using mean, median, range, and shape of distribution, b) interpreting data sets (e.g., draw conclusions, make predictions, and estimate values between and beyond given data points), c) evaluating interpretations of data with respect to correctness and completeness of interpretation.

• Clinical and Experimental Pediatrics
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• v.48 no.7
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• pp.711-715
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• 2005

Purpose : With the recent improved survival of extremely low birth weight infants(ELBWI), enteral feeding has become a major issue. This study investigates the effects of early enteral feeding in ELBWI on their morbidity, duration of hospitalization, and mortality. Methods : ELBWI admitted to the neonatal intensive care unit at Samsung Medical Center from November 1994 to April 2004 who survived more than 14 days were enrolled. ELBWI were divided into two groups : an early feeding group(EF), in which enteral feeding was started within 3 days after birth; and a late feeding group(LF), in which enteral feeding was started beyond 3 days after birth. 80 ELBWI came under EF, and 131 ELBWI under LF. Results : Birth weight and gestational age did not differ between the two groups. In EF, the time to achieve full enteral feeding and the duration of parenteral nutrition were significantly shorter than in LF. The incidence of bronchopulmonary dysplasia was significantly lower in EF, but the incidences of sepsis, necrotizing enterocolitis, and cholestasis were not different between the two groups. There was no difference in the survival rate between the two groups, but the duration of hospitalization was significantly shorter in EF. Conclusion : Early enteral feeding in ELBWI did not increase the incidence of necrotizing enterocolitis and sepsis, but rather decreased the incidence of bronchopulmonary dysplasia and shortened the duration of hospitalization.

• Applied Biological Chemistry
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• v.19 no.4
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• pp.219-226
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• 1976

To meet the need of protein feed and fine more efficient ways of returning waste to resources, we have carried out the study of the production of yeast for foods and feeds from the corn starch cake. The present study includes the method for acid-hydrolysis, the selection of yeast capable of utilizing hydrolyzate of the corn starch cake, and culture condition of Candida tropicalis under the liquid culture and the semisolid culture. Obtained results were as follows. 1. Hydrochloric acid was more excellent on the hydrolysis of the corn starch cake than sulfuric acid, and the yield of sugar was maximum, 57.2%, when the corn starch cake was hydrolyzed with 1.0% of hydrochloric acid at 2.0kg/cm for 30 minutes. 2. As the acid solution content was increased, more sugar was liberatedfrom the mixture, until the acid solution-substrate ratio reached 10:1. Beyond this point, no further increase was observed. To prepare the cultural medium of semisolid fermentation, a acid solution to substrate ratio of 3:1 appeared to be optimum. 3. Out of 6 yeast strains, Candida tropicalis had excellent growth on the hydrolyzate of the corn starch cake, and optimum temperature and initial pH were $30^{\circ}C$ and 6.0 respectively. 4. Optimum liquid medium of Candida tropicalis is ures 0.3%, potassium phosphate monobasic 0.15g and magnesium sulfate 0.04g in 100ml of the hydrolyzate of the corn starch cake, while optimum semisolid medium is ammonium chloride 0.4g, potassium phosphate monobasic 0.1%, magnesium sulfate 0.04%. 5. Candida tropicalis could assimilate the sugar in the hydrolyzate up to more than 88.75%, and a yield of dry yeast reached 19.13% to the corn starch cake under the liquid culture. 6. Compared to the that of the untreated corn starch cake, the cellulose content of the semisolid fermented cake decreased by 3.76% to 14.7%, whereas dry yeast contents increased by 13.89%.

• The Korean Journal of Physiology
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• v.16 no.1
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• pp.13-23
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• 1982

Effects of external pH and potassium concentrations on the electrical and mechanical properties were investigated on rabbit papillary muscle. Papillary muscles were perfused in horizontal chamber with Tris Tyrode solutions and action potential along with isometric tension was recorded simultaneously. Potassium concentrations were varied between 1 and 12 mM at low(6.9), normal(7.4) and high (7.9) external pH. The following results were obtained: 1) On rasing the potassium concentration from 1 to 12 mM resting membrane potentials decreased from $-88.8{\pm}2.8$ to $-66.4{\pm}1.2\;mV$ at normal pH and the amplitude of action potential decreased from $115.1{\pm}0.7$ to $97.5{\pm}2.8\;mV$. On lowering the potassium concentration, membrane hyperpolarized and at 1 mM potassium concentration resting potentials were $-107{\pm}2.2\;mV$. Duration of action potential especially $APD_{60}{\sim}APD_{90}$ increased($APD_{90}$: $214{\pm}15.8\;ms$ at 1 mM $K^+$ to $287{\pm}18.1\;ms$ at 12 mM $K^+$). 2) During acidosis membranes hyperpolarized by more than 20 mV within 1 min. and then slow recovery was observed during the following 10 min. During alkalosis membranes depolarized about 10 mV, which were maintained until washing with normal Tyrode solutions. 3) On lowering the external pH(7.9-6.5), duration of action potential increased progressively and it was most prominent at pH 6.5 and $K^+$ 1mM. 4) Magnitude of developed tension was $0.6{\pm}0.14\;g/mm^2$ at normal pH and potassium concentration (stimulus frequency : 60/min). Relative isometric tension to normal value increased along the increment of stimulus frequency($44.2{\pm}4.2%$ at 6/min to $271{\pm}86.7%$ at 180/min). Force-frequency relations were altered quantitatively during the perfusion with different external pH solutions. 5) Developed tension did not show marked variation within the range of $2{\sim}8\;mM$ potassium concentrations. Positive inotropism was observed at less than 2 mM $K^+$ and negative inotropism beyond 12 mM $K^+$ concentrations. From the above results we concluded that the effects of potassium ion concentration on electrical and mechanical properties of rabbit papillary muscle are related to the changes in surface negative charge due to acid base disturbances.

• Nuclear Engineering and Technology
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• v.55 no.3
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• pp.1061-1070
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• 2023

Over the last few years, lead-free inorganic metal perovskites have gained impressive ground in empowering satellites in space exploration owing to their material stability and performance evolution under extreme space environments. The present work has examined the versatility of eight such perovskites as space radiation shielding materials by computing their photon, charged particles and neutron interaction parameters. Photon interaction parameters were calculated for a wide energy range using PAGEX software. The ranges of heavy charged particles (H, He, C, N, O, Ne, Mg, Si and Fe ions) in these perovskites were estimated using SRIM software in the energy range 1 keV-10 GeV, and that of electrons was computed using ESTAR NIST software in the energy range 0.01 MeV-1 GeV. Further, the macroscopic fast neutron removal cross-sections were also calculated to estimate the neutron shielding efficiencies. The examined shielding parameters of the perovskites varied depending on the radiation type and energy. Among the selected perovskites, Cs₂TiI₆ and Ba₂AgIO₆ displayed superior photon attenuation properties. A 3.5 cm thick Ba₂AgIO₆-based shield could reduce the incident radiation intensity to half its initial value, a thickness even lesser than that of Pb-glass. Besides, CsSnBr₃ and La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ displayed the highest and lowest range values, respectively, for all heavy charged particles. Ba₂AgIO₆ showed electron stopping power (on par with Kovar) better than that of other examined materials. Interestingly, La_0.8Ca_0.2Ni_0.5Ti_0.5O₃ demonstrated neutron removal cross-section values greater than that of standard neutron shielding materials - aluminium and polyethylene. On the whole, the present study not only demonstrates the employment prospects of eco-friendly perovskites for shielding space radiations but also suggests future prospects for research in this direction.

• Culinary science and hospitality research
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• v.21 no.6
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• pp.242-254
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• 2015

Barley is a main food source, along with rice, in our dietary life that is easy to buy and process. It is required to develop a beverage base and barley syrup for desserts in order to raise utilization of barley beyond its present use in Sikhye (sweet fermented rice drink) and Jocheong (grain syrup) production. In pursuit of the goal to increase the usability of barley as an ingredient of processed food, this study examined the optimal preparation conditions of barley mash for barley syrup. In addition, the study prepared a barley syrup using saccharified barley liquid, analyzed quality characteristics, and conducted a sensory evaluation. Saccharified barley liquid(barley mash) was prepared with ratios of adding malt of unhulled barley germinated as 0 g(CON), 10 g(BM10), 20 g(BM20), and 30 g(BM30). The results of measuring pH under the varied conditions of saccharification temperatures from $50^{\circ}C$, $60^{\circ}C$, and $70^{\circ}C$, as well as time from 1 to 8 hours, treveal that the optimum condition for malt saccharification is $60^{\circ}C$ for 5 hours. By adding oligosaccharides and lemon juice to the saccharified barley liquid at the different ratios of added malt, this study measured quality characteristics(color value, viscosity, pH, sweetness) of barley syrup warmed up for 1 hour. As the result of measuring color in the barley syrup prepared by saccharified barley liquid, higher levels of added malt saw L-value decreased while a-value and b-value both increased. BMs30 showed the highest viscosity of $1,202.67{\pm}3.06$. As for pH, BMs30 was the highest at pH $3.57{\pm}0.02$. The result of the sensory evaluation of barley syrup showed the superior sensory characteristics of BMs20 in terms of color, flavor, sweetness, viscosity and overall quality.

• Journal of Preventive Medicine and Public Health
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• v.29 no.1 s.52
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• pp.113-131
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• 1996

This study was carried out to evaluate the relations among workers' general characteristics, work-related behaviors and health related behaviors in a steel industry with 1,134 workers in Pohang. The results were as follows; 1. The mean age of workers was 50 years old and working duration was 15 years and over. Most of them were married(94.5%) and had studied beyond high school (53.0%). They performed three shift work and most of them(63.0%) had experienced industial accidents. The frequency of noise and dust exposure was defined by a minimum of 6 hours per day, and workers complained about noise exposure(62.9%) and dust(55.6%). There were current smokers(67.7%), current drinkers(74.3%) and current exercising workers(32.3%) in the industry. The number of cigarette consumption in current drinkers was significantly high $(13.6{\pm}8.4\;pieces/day)$ and the alcohol consumption in current smokers was significantly high$(104.5{\pm}113.5\;g/wk)$. And the number of cigarette consumption of exercisers was significantly low and the alcohol consumption of exercisers was higher than non-exercisers. 3. The ratio of current smokers on frequent noise in exposed workers versus non-exposed workers was not significantly high but the current drinkers in frequent noise and dust exposed workers was significantly higher than non-exposed. 4. The normal levels of SGOT workers in non-smokers were significantly higher than in current smokers, and the normal levels of LFT (SGOT, SGPT, $\gamma-GTP$ workers in nondrinkers were significantly high. The normal levels of SBP and DBP workers in current smokers were not significantly high but were significantly high in non-drinkers. 5. The ratio of current smokers in voters unsatisfied with their job and working condition was higher than non-smokers, but the ratio of current drinkers in workers satisfied with their job and working condition were higher. 6. The significant factors for SGOT and $\gamma-GTP$ were age, the drinking amount and BMI. But the only significant factor for r-GTP was BMI. The significant factors for DBP were age, the alcohol consumption and BMI. And the significant factors for SBP were age, BMI.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.310-315
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• 2008

In this study, experimental study on the heating performance of a $CO_2$ heat pump water heater with a variation of operating conditions such as refrigerant charge amount, outdoor temperature, compressor frequency, EEV opening and water mass flow rate. Based on the test results, the optimum charge amount was 1800 g. At the water mass flow rates of 75, 85, 95 kg/hr, the water heating temperature was 62, 67, $74^{\circ}C$ and COP was 2.6, 2.8, 3.0, respectively. Besides, the water mass flow rate and compressor frequency were varied to maintain above the water heating temperature of $60^{\circ}C$ with the decrease of outdoor temperature. So, The compressor frequency increased beyond 65 Hz and the water mass flow rate was 45 kg/hr at the outdoor temperature of $-13^{\circ}C$, 65 kg/hr at $-8^{\circ}C$, 75 kg/hr at $-3^{\circ}C$ and 85 kg/hr at 2, $7^{\circ}C$. As the outdoor temperature decreased, the heating COP decreased by 2.5-39.8%.