• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.6
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• pp.469-477
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• 2017

In this paper, the floor vibration of an example concert hall building was measured and floor safety criteria were analytically checked through comparison between experimental and analytical results. The floor bottom plate model was constructed considering the composite effect and the analytical model was modified to have the natural frequency identical to the measured one. Also, time history analysis was conducted using the dynamic loads induced by human rhythmic movement during a musical performance, and the analytically calculated floor accelerations were similar to the measured one. Based on this model, the floor vibration level due to the group activities of about 400 persons, maximum available persons for the concert hall, was estimated. It was confirmed that the human induced dynamic loads applied to the column and beam would be much lower than the design strength. In addition, the horizontal acceleration level is just 2% of the design seismic load, so the concert hall is safe in both vertical and horizontal excitations by human rhythmic movements.

• Korean Journal of Environment and Ecology
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• v.12 no.1
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• pp.78-90
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• 1998

An objective of this study was to provide database for the planting disign of buffer green space. Types, planting structure, and effect of vuffer green space were investigated in five housing complexes of newtown of metropolitan area, Korea. Buffer green space in the study sites were constructed as mounding, slope, and plate. The number of species was found 20 tree and sub-tree species(10 evergreen and 20 deciduous species ) and 13 shrub species. These species were planted in one-storyed planting structure and there was no difference with ornamental species in the urban parks. Effect of sound proof by the buffer green space was recognized but sound level in four types among the seven types was observed above standard sound level for housing complex(65dB). Effect of sound proof was especially most effective in the mounding type. It was found that planting density and index of plant crown volume were mot satisfied to the function of buffer green space because of lower density and crown volume than natural vegetation per unit. Based on these results, this study suggested that buffer green space is desirable to be developed in the mounding type over two meters height with multi-layer planting model. In addition, there is needed to consider vegetation structure of natural forest around the developing site.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.12
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• pp.938-943
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• 2018

Thin nano-sized fibres were prepared by an electrospinning method. The spinning appratus consisted of pump for polymer injection, nozzle and nozzle rotus, and an aluminum plate collected the polymer fibers. Its surface was chemically modified for selective improved adsorption of carbon monoxide at indoor level. The chemical activation enabled to form the fibres 250-350 nm in thickness with pore sizes distributed between 0.6 and 0.7 nm and an average specific surface area of $569m^2/g$. The adsorption capacities of pure (100%) and indoor (0.3%) $CO_2$, of which level frequently appears, at the ambient condition were improved from 1.08 and 0.013 to 2.2 and 0.144 mmol/g, respectively. It was found that the adsorption amount of $CO_2$ adsorbed by the chemically activated carbon nanofiber prepared through chemical activation would vary depending on the ratio of specific surface area and micropores. In particular, chemical interaction between adsorbent surface and gas molecules could enhance the selective capture of weak acidic $CO_2$.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2019.10a
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• pp.46-46
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• 2019

The experiments were performed in the Jinan (elevation: 300 meters above sea level), Jeollabuk-do. Seedlings (n = 63 per $3.3m^2$) of ginseng cultivar (Cheonpung, Yeonpung) were planted on April 10, 2015. Shading material of plastic film house was blue-white film. Before the Planting seedling, silicate (3 kg/10 a) or chitosan (40 kg/10 a) was fertilized and foliar sprayed on the leaves 1000 times dilution solution once a month from May to September every year. The growth results of 5-year old ginseng surveyed in 2018 are as follows. The average air temperature in the plastic film house was the highest at $26.6^{\circ}C$ and $26.5^{\circ}C$ in July and August, respectively, and the highest temperature was $40.5^{\circ}C$ in July. The maximum daily temperature of $35^{\circ}C$ or more was 30 days, with the average soil temperature being $24.9^{\circ}C$ in August. The chemical properties of the test soil are as follows. pH was 6.4~6.9 level and EC was 0.35~0.46 dS/m. The organic matter content was 33.5~41.4 g/kg, and available-P content was 251.9~306.8 mg/kg. Exchangeable cations contents, such as K, Ca and Mg were all the appropriate ranges. The soil microbial density surveyed by the dilution plate method was 10~50 times higher than that of control (Non-treatment) and actinomycete density was 3~6 times higher. Pathogens of the genus Fusarium by Metagenome analysis decreased 91.3% and 68.2% respectively in the foliar sprayed of chitosan and soluble-silicate. The light intensity (PAR) in the blue-white film plastic film house gradually increased until July and then decereased, with the average of light intensity in March-October was $120.3umol/m^2/s$. The growth of aerial parts such as plant height and stem length was better than non-sprayed group in silicate or chitosan treatments and Yeonpung cultivar was superior to the Cheonpung cultivar. The SPAD value was higher in Yeonpung cultivar foliar sprayed with soluble-silicate. The growth of underground parts such as root length and taproot length were better in chitosan and soluble-silicate treatment than control, especially in Yeonpung cultivar foliar sprayed with chitosan was good in taproot length and taproot diameter, and fresh weight of root was 60.1 g. Ginsenoside contents were 24.9 mg/g and 22.4 mg/g, in the Cheonpung cultivar foliar sprayed with soluble-silicate or chitosan respectively, 28% and 15% higher than control (19.5 mg/g). The incidence of disease by Alteraria panax and Botrytis cinerea was 3~9% and 4~9%, respectively. High temperature damage rate was 3~5%.

• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.71-77
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• 2011

Recently, non-destructive stress measurement method using magnetic anisotropy sensor has been applied to the construction site such as steel bridges and steel pipes. In addition, steel rib used in the tunnel construction site was found to be possible to measure the stress by non-destructive method. In this study, steel loading experiments using magnetic anisotropy sensor developed in Japan and strain gauges were conducted to derive stress sensitivity curve for domestic steel SS400. Also, additional steel loading experiments and numerical analysis were performed for evaluation of applicability for non-destructive stress measurement method using magnetic anisotropy sensor. As a result of this study, stress sensitivity curves for domestic steel SS400 were derived using output voltage measured by magnetic anisotropy sensor and average of stress measured by strain gauges depending on the measurement location. And as a result of comparing additional steel loading experiments with the numerical analysis, error level of magnetic anisotropy sensor is around 20MPa. When considering the level of the yield stress(245MPa) of steel, in case of using magnetic anisotropy sensor in order to determine the stress status of steel, it has sufficient accuracy in engineering. Especially, magnetic anisotropy sensor can easily identify the current state of stress which considers residual stress at steel structure that stress measurement sensor is not installed, so we found that magnetic anisotropy sensor can be applied at maintenance of steel structure conveniently.

• Korean Journal of Food Science and Technology
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• v.46 no.1
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• pp.108-114
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• 2014

To analyze the hazards associated with cucumber and hot pepper cultivation areas, a total of 72 samples were obtained and tested to detect the presence of biological (sanitary indicative, pathogenic bacteria and fungi) and chemical hazards (heavy metals and pesticide residues). The levels of sanitary indicative bacteria (aerobic plate counts and coliforms) and fungi were ND-7.2 and ND-4.8 log CFU/(g, mL, hand, or $100cm^2$) in cucumber cultivation areas, and ND-6.8 and 0.4-5.3 log CFU/(g, mL, hand, or $100cm^2$) in hot pepper cultivation areas. More specifically, the soil of hot pepper cultivation areas was contaminated with coliforms at a maximum level of 5.6 log CFU/g. Staphylococcus aureus was detected only in glove samples at a level of 1.4 log CFU/$100cm^2$ and Bacillus cereus was detected in the majority of samples at a level of ND-4.8 log CFU/(g, mL, hand, or $100cm^2$). Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella spp. were not detected. Heavy metal (Zn, Cu, Ni, Pb, and Hg) chemical hazards were detected at levels lower than the regulation limit. Residual insecticides were not detected in cucumbers; however, hexaconazole was detected at a level of 0.016 mg/kg (maximum residue limit: 0.3 mg/kg) in hot peppers.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.875-882
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• 2021

To minimize occupational noise induced hearing loss, it is recommended that workers should not be exposed to noise levels exceeding 85 dBA for over 8 h. In the present study, noise exposure levels were measured for seven workers based on their tasks on a training ship. The A-weighted noise exposure level (L_ex,24h) was measured by taking into account the A-weighted equivalent continuous sound level (L_Aeq,i), duration (h) and noise contribution (L_ex,24h,i) from the workers' locations. Results are thus obtained for different job categories as follows: officer group L_ex,24h=56.1 dB, navigation crew L_ex,24h=58.9 dB, navigation cadet L_ex,24h=62.0 dB, ship's cook L_ex,24h=64.3 dB, engine cadet L_ex,24h=91.1 dB, engineer L_ex,24h=91.1 dB, and engine crew L_ex,24h=95.1 dB. It was determined that the engineers, engine crews, and engine cadets in charge of machinery must wear hearing protection devices. By wearing hearing protection devices when working in highly noisy engine rooms, it is estimated that the noise expose levels could be reduced by the following amounts: engineer L_ex,24h=23.1 dB, engine Crew L_ex,24h=24.4 dB, and engine cadet L_ex,24h=21.5 dB. Moreover, if the no. 2 lecture room and mess room bottom plates in the cadets accommodations were improved to the 64 mm A-60-class floating plates, then further reductions are possible as follows: navigation cadet L_ex,24h=4.3 dB and engine cadet L_ex,24h=1.8 dB.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.9
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• pp.1270-1278
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• 2010

Dietary effects of chicken treated with Hwangki-Beni Koji sauces (HBS) on serum and hepatic lipid profiles in rats fed high a fat and high cholesterol diet were investigated. Experimental plots (5 rats per each group) were divided into normal control diet group (NC), high fat and high cholesterol diet group (HFC), HFC plus 15% base sauce treated chicken supplemented diet group (HFC-BS), HFC plus 15% HBS-treated chicken supplemented diet group (HFC-HBS), and fed for 5 weeks. Feed intakes in HFC-HBS group were higher than those of HFC and HFC-BS groups, whereas body weight gain and feed efficiency ratio of the HFC-HBS group were lower than those of the HFC and HFC-BS groups. Serum alanine aminotransferase and aspartate aminotransferase activities of HFC-HBS group were significantly lower than those of HFC and HFC-BS groups. Level of serum triglyceride, total cholesterol and LDL-cholesterol in HFC-HBS group were 34.06%, 6.28% and 31.00% lower than those of HFC-BS group, respectively, whereas HDL-cholesterol level and atherogenic index in HFC-HBS group were 1.72-fold higher and 2.52-fold lower, respectively, than those of HFC-BS group. Level of hepatic total lipid, triglyceride and total cholesterol in HFC-HBS group were 9.53%, 5.25% and 22.20% lower than those of HFC-BS group, respectively. In the morphological results of liver, the hepatocytes of central vein lesion and intact hepatic cell plate are preserved well from steatosis in HFC-HBS group, whereas the hepatocytes in HFC and HFC-BS groups are distended by accumulation of multiple fat droplets, and sinusoids are occluded. In the above results, we expected that chicken treated with Hwangki-Beni Koji sauce may have functionalities of anti-obesity, anti-cholesterol and also, lowering anti-atherogenic index in high fat and high cholesterol diets.

• Journal of Food Hygiene and Safety
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• v.30 no.3
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• pp.249-257
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• 2015

The purposes of this study were to develop a small scale post-harvest facility, and consequently to evaluate the effects of applying the facility along with hygiene education on the level of microbial safety in Korean leeks production. A total of 135 samples were collected at three Korean leeks farms in Yangju, Gyeonggi province. Food safety indicators (Aerobic plate count (APC), coliform count, and Escherichia coli) and foodborne pathogens (E. coli O157:H7, Salmonella spp., Staphylococcus aureus, Listeria monocytogenes, and Bacillus cereus) on/in the samples were assessed. The microbial load measured as APC with harvesting tools such as comb, chopping board, and knife, at the farms where the small scale post-harvest facility had been operated (Farms A and B) was lower than that at another farm having no post-harvest facility (Farm C) by 1.44~2.33 log CFU / $100cm^2$. Moreover, the chopping board from Farm C was observed being contaminated with B. cereus at 6.03 log CFU / $100cm^2$. The coliform counts from the samples increased by 0.57~1.89 log CFU/g after leeks was submerged in ground water for washing. E. coli was recovered from leeks, soil, and the ground water used in the washing process, while no E. coli O157:H7, Salmonella spp., and L. monocytogenes was detected. Our results indicated that the small scale post-harvest facility developed in this study as well as the hygiene education played an important role in enhancing the level of microbial food safety in the leeks production environment. However, a disinfection technique could be needed during the washing step in order to prevent a potential contamination.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.916-923
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• 1998

To provide more information on the enteric pathogen Campylobacter jejuni in the view of food sanitation, survival characteristics of two strains of C. jejuni in the different conditions were investigated. When $10^7{\;}or{\;}10^3{\;}per{\;}ml$ of C. jejuni cells were inoculated in the supplemented Brucella broth and kept at $42^{\circ}C,{\;}25^{\circ}C{\;}and{\;}5^{\circ}C$ under the static aerobic condition for 7 days, organisms exponentially proliferated to $a{\;}>10^8$, even in the $10^3{\;}per{\;}ml$ inoculated-sample at $42^{\circ}C{\;}for{\;}1{\sim}2{\;}days$ and the considerable level of viability maintained during 7 days. At $5^{\circ}C$, most of the initial level of organisms survived at the early period and only $a{\;}<{\;}0.5-log_{10}$ cells decrease were observed during the 7 days. At $25^{\circ}C$, a remarkable number of C. jejuni declined within $1{\sim}2{\;}days$ and showed undetectable level of cells after 4 days. When sterile milk and minced chicken meat were artifically inoculated with $10^7{\;}per{\;}ml$ of C. jejuni, mostly, a $1-to{\;}2-log_{10}$ count decrease occurred at $42^{\circ}C{\;}and{\;}5^{\circ}C$ while $a{\;}>3{\;}log_{10}$ decrease at $25^{\circ}C$ during 7 days. Unexpectedly, no colonies appeared on the plate inoculated from the minced chicken meat sample kept at $42^{\circ}C$ after 4 days. The results suggest that C. jejuni contaminated to food can survive at the refrigeration temperature whereas they are sensitive to at the room temperature. Also, it is shown that the growth of C. jejuni at the optimal temperature may vary to the food sources.