• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.10
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• pp.100-106
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• 2019

Ground and high altitude simulated combustion experiments were conducted using a liquid rocket engine with hydrogen peroxide and kerosene as the propellant. A ground and high altitude simulated combustion test facility was constructed by installing a high altitude model diffuser and TMS (Thrust Measuring System) on a vertical combustion test bench. The thrust characteristics according to altitude were investigated using the combustion test equipment. The diffuser was designed on a 1:4.8 scale to verify the characteristics of the high diffusing diffuser and starting pressure. The cold flow tests were conducted using nitrogen gas, and the performance characteristics and starting characteristics of the scale down diffuser were verified. A diffuser and TMS were installed on the vertical combustion test bench, and the thrust correction equations for the system resistance were derived. The thrust correction equations were derived from the step test and vacuum step test before the actual hot firing test. Nozzles with an operating altitude of 10km were designed. Hot firing tests were conducted to analyze the thrust characteristics according to the operating altitude changes. The actual thrust was calculated using each correction equation with the thrust value measured by the TMS.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.3
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• pp.177-186
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• 1970

The spawning of the abalone, Haliotis discus hannai, was induced In October 1969 by air ex-position for about 30 minutes. At temperatures of from 14.0 to $18.8^{\circ}C$, the youngest trochophore stage was reached within 22 hours after the egg was laid. The trochophore was transformed into the veliger stage within 34 hours after fertilization. For $7\~9$ days after oviposition the veliger floated in sea water and then settled to the bottom. The peristomal shell was secreted along the outer lip of the aperture of the larval shell, and the first respiratory pore appears at about 110 days after fertilization. The shell attained a length of 0.40 mm in 15 days, 1.39 mm in 49 days, 2.14 mm in 110 days, 5.20 mm in 170 days and 10.00 mm in 228 days respectively. Monthly growth rate of the shell length is expressed by the following equation :$L=0.9981\;e^{0.18659M}$ where L is shell length and M is time in month. The density of floating larvae in the culture tank was about 10 larvae per 100 co. The number of larvae attached to a polyethylene collector ($30\times20\;cm$) ranged from 10 to 600. Mortality of the settled larvae on the polyethylene collector was about $87.0\%$ during 170 days following settlement. The culture of Nauicula sp. was made with rough polyethylene collectors hung at three different depths, namely 5 cm, 45 cm and 85 cm. At each depth the highest cell concentration appeared after $15\~17$ days, and the numbers of cells are shown as follows: $$5\;cm\;34.3\times10^4\;Cells/cm^2$$ $$45\;cm\;27.2\times10^4\;Cells/cm^2$$ $$85\;cm\;26.3\times10^4\;Cells/cm^2$$ At temperatures of from 13.0 to $14.3^{\circ}C$, the distance travelled by the larvae (3.0 mm In shell length) averaged 11.36 mm for a Period of 30 days. Their locomation was relatively active between 6 p.m. and 9 p.m., and $52.2\%$ of them moved during this period. When the larvae (2.0 mm in shell length) were kept in water at $0\;to\;\~1.8^{\circ}C$, they moved 1.15cm between 4 p.m. and 8 p.m. and 0.10 cm between midnight and 8 a.m. The relationships between shell length and body weight of the abalone sampled from three different localities are shown as follows: Dolsan-do $W=0.2479\;L^{2.5721}$ Huksan-do $W=0.1001\;L^{3.1021}$ Pohang $W=0.9632\;L^{2.0611}$

• Journal of Nutrition and Health
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• v.48 no.6
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• pp.519-529
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• 2015

Purpose: The purpose of this study was to examine the prevalence of food insecurity in Korean elderly and to analyze the health status as well as food and nutrient intakes according to food insecurity status. Methods: A total of 939 elderly subjects (over 65 years old) were used in our analysis from the fifth 2010 Korean National Health and Nutrition Examination Survey (KNHANES V-1). The variables consisted of general characteristics, physical and mental health, nutrient intake, rate of deficient intake of energy and nutrients compared with Dietary Reference Intakes for Koreans (KDRIs) and food quality and diversity according to the status of food insecurity. Food insecurity status was measured using a self-reported food security questionnaire on the dietary situation in the previous year, and participants were classified according to three groups: food secure group, mildly food insecure group, and moderately/severely food insecure group. Results: The proportion of the food insecure group was approximately 67% and the food insecure group had lower income and educational status than the food secure group. Food insecurity was associated with worse physical and mental health status after adjusting potentially confounding variables. The results showed that food insecurity in Korean elderly significantly affected mental health (including stress cognition, depression experience, and suicide thoughts) which exceeded stages of physical health. In addition, food insecurity showed significant association with low nutrient intake and high rate of deficient intakes of energy and nutrients compared with KDRIs, and a reduction of dietary quality and diversity was indicated in the food insecure group. Conclusion: This study concludes that the prevalence of food insecurity may affect the physical and mental health as well as dietary intake of the elderly Korean population. Therefore, food insecurity should be considered as an important public health issue in Korea.

• Korean Journal of Microbiology
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• v.47 no.4
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• pp.356-363
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• 2011

The accidental releases of total petroleum hydrocarbons (TPH) due to oil spills frequently ended up with soil and ground water pollution. TPH may be degraded through physicochemical and biological processes in the environment but with relatively slow rates. In this study an attempt has been made to develop an integrated chemical and biological treatment technology in order to establish an efficient and environment-friendly restoration technology for the TPH contaminated soils. A Fenton-like reaction was employed as a preceding chemical treatment process and a bioaugmentation process utilizing a diesel fuel degrader consortium was subsequently applied as a biological treatment process. An efficient chemical removal of TPH from soils occurred when the surfactant OP-10S (0.05%) and oxidants ($FeSO_4$ 4%, and $H_2O_2$ 5%) were used. Bioaugmentation of the degrader consortium into the soil slurry led to an increase in their population density at least two orders of magnitude, indicating a good survival of the degradative populations in the contaminated soils ($10^8-10^9$ CFU/g slurry). TPH removal efficiencies for the Fenton-treated soils increased by at least 57% when the soils were subjected to bioaugmentation of the degradative consortium. However, relatively lower TPH treatment efficiencies (79-83%) have been observed in the soils treated with Fenton and the degraders as opposed to the control (95%) that was left with no treatment. This appeared to be due to the presence of free radicals and other oxidative products generated during the Fenton treatment which might inhibit their degradation activity. The findings in this study will contribute to development of efficient bioremediation treatment technologies for TPH-contaminated soils and sediments in the environment.

• Journal of dental hygiene science
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• v.17 no.4
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• pp.298-305
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• 2017

This study aimed to investigate the relationship between sleep duration and periodontitis in adult Korean women. This cross-sectional study was based on the 2014 Korea National Health and Nutrition Examination Survey (KNHNES). We selected the data from 3,292 women (over 19 years of age) out of 7,550 participants for analysis, after excluding data from men. Complex logistic regression analysis was performed to determine the effect of sleep duration on the risk of periodontitis; the crude and adjusted odds ratios (ORs) were calculated. The risk of periodontitis was higher in participants who had a sleep duration of 7 hours or more, than in those with less than 7 hours (crude OR) by 1.37 times (95% confidence interval [CI], 1.13~1.65). The adjusted OR of the participants after adjusting for the sample characteristics of the participants (age, education level, income level, diabetes, hypertension, obesity) was 1.04 times (95% CI, 0.82~1.32), but the risk for periodontitis was slightly higher, though not statistically significant. This study confirmed the relationship between sleep duration and the risk of periodontitis in Korean women. Therefore, it is necessary to develop and implement a comprehensive health promotion program that can improve the proper sleeping habits of adult women in Korea and to combine oral hygiene management programs to prevent periodontal disease.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.1
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• pp.21-29
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• 1988

This study was carried out to develop the powdered Katsuobushi (a kind of boiled, smoked, and dried fish product which is used for seasoning soup as it is.) using skipjack as a natural flavoring substance. The processing conditions of the powdered Katsuobushi and the changes of taste compounds during processing of the products were examined. In preparation of the powdered Katsuobushl, frozen skipjack was thawed, beheaded, gutted, filleted and then sliced to 1cm of thickness. The silted meats were boiled in skipjack extract for 20 minutes, and then it was smoked for, 3 times to $10\~12\%$ moisture content at $80^{\circ}C$ for 8 hours. The smoked - dried meats were followed to be 50 mesh of particle size. The effect of slicing and boiling in skipjack meat extract on enhancing flavor and on preventing lipid oxidation of product during processing were observed. The moisture content and crude lipid content of the powdered Katsuobushi was in the range of 11 to $12\%$ and 4.3 to $4.8\%$, respectively. The taste compounds of the product were nucleotides and their related compounds, 1135.8mg/100g ; free amino acid and related compounds, 2210.2mg/100g ; non-volatile organic acids, 1148.0mg/100g ; and total creatinine. 592.1mg/100g on dry basis, and small amount of betaine and TMAO. The major elements of mineral in the product were found to be K, Mg, Na, and Ca. The content of IMP was 542.0mg/100g, and major free amino acids were found to be histidine, anserine, taurine, carnosine and alanine of which occupied to $83.6\%$ of total free amino acids. In non -volatile organic acids, major ones were lactic acid, succinic acid, pyroglutamic acid and $\alpha-ketoglutaric$ acid. From the results of the chemical experiments and sensory evaluation, we may conclude that the flavor of the product from present experiment is more desirable than that of conventional products although the processing time used were much shortened than that of conventional method, and it can be commercialized as a seasoning powder.

• Korean Journal of Environmental Agriculture
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• v.30 no.1
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• pp.52-59
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• 2011

BACKGROUND: This study was performed to investigate pre-harvest residue limit (PHRL) in Chwinamul, to estimate biological half-life for residue of each pesticide. Chwinamul was sprayed with pesticides of standard and double application rate. Chlorfenapyr and fenarimol were sprayed once on Chwinamul at 10 days before harvest, and it was sampled 7 times and analysed the residual change of two pesticides. METHODS AND RESULTS: Chwinamul sample was extracted with acetonitrile and partitioned with dichloromethane, and pesticide residues were determined with GCECD. Method quantitation limit (MQL) of chlorfenapyr was 0.10 mg/kg and that of fenarimol was 0.02 mg/kg. Recoveries of chlorfenapyr at two fortification levels of 1.0 and 5.0 mg/kg were $94.2{\pm}$1.70 and $99.0{\pm}1.61%$, respectively. Recoveries of fenarimol at two fortification levels of 0.2 and 1.0 mg/kg were $92.1{\pm}2.14$ and $83.1{\pm}1.98%$, respectively. CONCLUSION(s): The biological half-lives of chlorfenapyr were about 3.5 days at standard application rate, and 3.4 days at double application rate. The biological half-lives of fenarimol were about 6.0 days at standard application rate, and 5.9 days at double application rate. The PHRLs of chlorfenapyr were recommended as 13.02 and 6.25 mg/kg for 10 and 5 days before harvest, respectively. And the PHRLs of fenarimol were recommended as 2.80 and 1.67 mg/kg for 10 and 5 days before harvest, respectively.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.63 no.1
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• pp.41-47
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• 2018

Soybean sprouts have good digestibility, high isoflavone content compared with soybean seeds, and large amounts of aspartic acid, which is effective in eliminating hangovers. However, the region between the cotyledon and hypocotyl in soybean sprouts appears purple, the product value of soybean sprouts reduces. To date, the scientific correlation among factors such as growth temperature, spray water temperature, and cultivation periods for soybean varieties related to purple color expression between the cotyledon and hypocotyl of soybean sprouts are unknown. The purpose of this study was to identify the factors regulating the expression of purple color between the cotyledon and hypocotyl of soybean sprouts. Of 15 Korean soybean varieties with purple color in the hypocotyls and flowers, 9 varieties, including Sowonkong, Wonhwang, Sinhwa, Eunhakong, Pungsannamulkong, Paldonamulkong, Kwangankong, Shingang, and Jangki showed purple color between the cotyledon and hypocotyl of sprouts. However, the remaining six cultivars, including Dachae, Myeongjunamulkong, Sobaeknamulkong, Sojinnamulkong, Anpyeong, and Jonam, did not show purple color. The proportion of soybean sprouts with purple hypocotyls was the lowest at $26^{\circ}C$ and there was no significant difference at the other three cultivation temperature conditions ($17^{\circ}C$, $20^{\circ}C$, and $23^{\circ}C$). Similar to the results of the cultivation temperature experiment at five different spray water temperatures ($10^{\circ}C$, $17^{\circ}C$, $20^{\circ}C$, $23^{\circ}C$, and $26^{\circ}C$), the proportion of soybean sprouts with purple hypocotyls was the highest at the lowest spray water temperature ($10^{\circ}C$), and lowest at the highest temperature. Additionally, there was no purple color expression in soybean sprout hypocotyls on the $3^{rd}$ day after soybean sprouting. However, the highest expression level was observed on the $4^{th}$ day. Then, on the $5^{th}$ day, the proportion of soybean sprouts with purple hypocotyls reduced significantly, compared with that on the $4^{th}$ day. The results showed that interaction among these factors under cultivation conditions was remarkably effective for the expression of purple color in hypocotyls under the dark condition. These results suggested that cultivation temperature and spray water temperature for purple color expression in soybean sprout hypocotyls are the most important factors in the sprout cultivation environment.

• Journal of Korean Home Economics Education Association
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• v.29 no.4
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• pp.1-14
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• 2017

This study described the status of family dining and personality of adolescents, determined the differences in family dining according to personal variables, and examined the relationship between family dining and personality in adolescence. The Data were collected from self-reported inventory of the middle and high school students in a city and 1,259 data copies were used for analyses. Data were analyzed for frequency, percentage, mean, standard deviation, Cronbach's ${\alpha}$, t-test, ANOVA, scheffe test, and multiple regression analysis using SPSS/PC 18.0 program. The results obtained were as follows. First, as for the weekly family dining frequency, more than 7 times had the most number of responses(44.2%), followed by 1~2 times(20.8%), 3~4 times(18.1%), 5~6 times(12.9%). The average scores for family dining perception and family dining attitudes were 3.75 and 3.42 on a 5-Likert scale, respectively, which means moderately high. But, family dining rules was 2.80, which means moderate. Agreeableness was the highest(3.68) among the personality components followed by Openness/intellect(3.42), Extraversion(3.33), Conscientiousness(3.14), and Emotional Stability(3.05) out of 5-point Likert scale. Second, there were statistically significant differences in family dining frequency, family dining perception, family dining rules, and family dining attitudes depending on the gender, school level, and the father's academic attainment. Third, family dining frequency, family dining perception, and family dining attitudes had statistically significant influence on the personality of adolescents after personal variables were considered. But, there was no significant relationship between family dining rules and the personality. The outcomes indicate that family dining affects the personality of adolescents. School needs to offer quality programs with various teaching methods to enhance family dining frequency, family dining perception, and family dining attitudes.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.5
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• pp.279-284
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• 2008

This study was performed to investigate effect of different soil managements on physical properties and microbial activities in volcanic ash citrus orchard soil. Experiment plots had managed to control weeds on soil for 4 years with clean cultivation (CCM) used with herbicide, natural sod cultivation (NSCM), kentucky blue grass sod cultivation (KBG). Soil samples were taken on October, in both 1998 and 2000 from 3 experimental plots. In NSCM, Soil hardness was lower at 11.8 mm than in CCM. And water stable Aggregation coefficient(>0.5 mm) was high at 26.7% compared with CCM. Soil bulk density and porosity showed no significant among the treatments. Soil acid phosphatase was high in sod cultivation plots and the amount of microbial biomass C was about twice higher at $525.4mg\;kg^{-1}$ in KBG than in CCM. Conclusionally, Sod cultivation improved soil physical properties such as aggregation, hardness and increased microbial activities compared with clean cultivation in citrus orchard soil. Soil total PLFA, acid phosphatase, and microbial biomass C contents were investigated on May in nonvolcanic ash citrus soil. Soil samples were collected at 5 sites each; convention cultivation grown with herbicide, natural sod cultivation grown with 1/2 chemicals, organic cultivation. That sites have been managed for 5 years over. PLFA contents were two times higher at $112.2n\;mol\;g^{-1}$ in organic cultivation than in convention cultivation. According to the PLFA indicator, Gram negative bacteria and actinomycetes in organic cultivation were high compared with convention cultivation, which were at 15.1%, 6.6%, respectively. Soil microbial biomass C contents was about twice higher in organic cultivation than in convention cultivation. Soil acid phosphatase was high at 17.6% in organic cultivation compared with convention cultivation.