• Journal of Microbiology and Biotechnology
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• v.25 no.10
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• pp.1670-1679
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• 2015

Two hollow fiber membrane biofilm reactors (HF-MBfRs) were operated for autotrophic nitrification and hydrogenotrophic denitrification for over 300 days. Oxygen and hydrogen were supplied through the hollow fiber membrane for nitrification and denitrification, respectively. During the period, the nitrogen was removed with the efficiency of 82-97% for ammonium and 87-97% for nitrate and with the nitrogen removal load of 0.09-0.26 kg NH₄⁺-N/m³/d and 0.10-0.21 kg NO₃^--N/m³/d, depending on hydraulic retention time variation by the two HF-MBfRs for autotrophic nitrification and hydrogenotrophic denitrification, respectively. Biofilms were collected from diverse topological positions in the reactors, each at different nitrogen loading rates, and the microbial communities were analyzed with partial 16S rRNA gene sequences in denaturing gradient gel electrophoresis (DGGE). Detected DGGE band sequences in the reactors were correlated with nitrification or denitrification. The profile of the DGGE bands depended on the NH₄⁺ or NO₃^- loading rate, but it was hard to find a major strain affecting the nitrogen removal efficiency. Nitrospira-related phylum was detected in all biofilm samples from the nitrification reactors. Paracoccus sp. and Aquaspirillum sp., which are an autohydrogenotrophic bacterium and an oligotrophic denitrifier, respectively, were observed in the denitrification reactors. The distribution of microbial communities was relatively stable at different nitrogen loading rates, and DGGE analysis based on 16S rRNA (341f /534r) could successfully detect nitrate-oxidizing and hydrogen-oxidizing bacteria but not ammonium-oxidizing bacteria in the HF-MBfRs.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.45-52
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• 2009

Naphthalene-degrading bacteria Pseudomonas aeruginosa CZ6 isolated from contaminated soil can adhere to crystal naphthalene and produce extracellular polymeric substance. LB, YM and MSM medium were used as culture mediums to investigate the formation of biofilm. Biofilm was developed the most in LB medium by Pseudomonas aeruginosa CZ6. In the culture, strain CZ6 growth was rarely affected by naphthalene concentration. Optimal culture condition was $30^{\circ}C$ and pH 7 at 0.10% substrate and 150 rpm shaking. The effect of culture medium on naphthalene degradation in the two soil slurry system was evaluated. The initial degradation rate of naphthalene was highest in the MSM medium of soil slurry. However, the sorbed naphthalene was rapidly degraded at the LB medium when naphthalene availability in liquid was limited. The results of this study suggest that biofilm formation and extracellular polymeric substance production increased bioavailability of soil sorbed naphthalene.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.12
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• pp.1557-1566
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• 2004

A flame extinction phenomenon is a typical unsteady process in combustion. Flame extinction is characterized by various physical phenomena, such as convection, diffusion, and the production of heat and mass. Flame extinction can be achieved by either increasing the strain rate or curvature, by diluting an inert gas or inhibitor, or by increasing the thermal or radiant energy loss. Though the extinction is an inherently transient process, steady and quasi-steady approaches have been used as useful tools for understanding the flame extinction phenomenon. Recently, unsteady characteristics of flames have been studied by many researchers, and various attempts have been made to understand unsteady flame behavior, by using various extinction processes. Representative parameters for describing flame, such as flame temperature, important species related to reactions, and chemi-luminescence of the flame have been used as criterions of flame extinction. In these works, verification of each parameter and establishing the proper criterions of the extinction has been very important. In this study, a time-dependent flame temperature and an OH radical concentration were measured using optical methods, and the instantaneous change of the flame luminosity was also measured using a high-speed ICCD (HICCD) camera. We compare the unsteady extinction points obtained by three different methods, and we discuss transient characteristics of maximum flame temperature and OH radical distribution near the extinction limit.

• Journal of the Korea Concrete Institute
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• v.22 no.5
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• pp.625-632
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• 2010

The moduli of concrete has been determined by various testing methods. The impact resonance (IR) method has been shown to be truly a simple nondestructive testing method which produces consistent results. It is possible to determine not only the modulus but also damping ratio from the IR test. However, the values of elastic modulus and damping ratio of concrete from the test is known to be affected by various test conditions including, specimen support condition, impact steel ball size and sampling rate. In this study, the optimum IR test conditions are suggested and validated experimentally. The test results showed that the recommended test conditions yielded a variation of resonant frequency within ${\pm}0.3%$ and damping ratio ${\pm}10.0%$. In addition, the modulus from the IR test was comparable to that from a static test when the effect of strain amplitude was properly taken into account.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.11
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• pp.1672-1681
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• 2002

To evaluate the thermal environments and the workload of farmers in the rice field in summer, this study investigated rice farmers' physiological, psychological responses, work postures, work clothes, air temperature and air humidity during the spraying pesticide in the rice field. Five career farmers (3 males, 2 females) volunteered as the subjects. During the spraying pesticide in the rice field, physiological responses were monitored continuously. The results were as follows. l. Farmers wore only raincoats not pesticide-proof clothing. 2. The value of WBGT, rectal temperature($T_{re}$), mean skin temperature(${\={T}}_{sk}$) were $24.9∼28.9^{\circ}C,\;37.8({\pm}0.3)^{\circ}C\;and\;33.6({\pm}0.6)^{\circ}C$, respectively. Clothing microclimate temperature($T_{cl}$) on the chest and back were $32.5({\pm}2.6)^{\circ}C\;and\;33.6({\pm}2.6)^{\circ}C$, respectively(p<0.00l). Humidity inside of the clothing ($H_{cl}$) was over 80%RH and heart rate(HR) was 112(${\pm}27$)bpm. We evaluated that the spraying pesticide was 'heavy work' by the Tre and HR. To four subjective questionnaires, all farmers expressed 'hard, hot, humid and uncomfortable' without individual difference at the end of works. We suggested that 1) the spraying pesticide in the rice field was a heavy work, 2) because the workload of farmers in the raincoat/pesticide-proof clothing can't be evaluated by only WBGT, assessors should measure physiological, psychological responses as well as thermal environments, 3) to alleviate farmers' heat strain, clothing manufacturers must consider not only the improvement of textile materials and clothing weight but also the designing of personal cooling equipment.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.21-28
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• 2020

The stem extract from Pyrus serotina var has natural antioxidant ability, but the extraction method does not result in a soluble compound in cosmetic formulations. This study investigated the cosmetic efficacy of the Pyrus serotina var stem extract and its epidermis permeation ability when combined with polymer micelles and a cell penetrating peptide. The total concentration of polyphenol compounds was determined to be 103.1644 ± 1.38 mg/g in the ethanol extract and 78.97 ± 1.45 mg/g in the hydrothermal extract. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging effects were 55.94 ± 0.22% in the ethanol extract at 1,000 mg/L. Superoxide dismutase (SOD) activity rates were 104.05 ± 3.28% in the ethanol extract at 62.5 mg/L. The elastase inhibition rate was 67.21 ± 2.72% in the ethanol extract at 1,000 mg/L. An antimicrobial effect was observed in the Propionibacterium acnes strain. In the epidermal permeability experiment, it was confirmed that formulation of the polymer micelle containing the Pyrus serotina var stem extract and cell penetrating peptide (R6, hexa-D-arginine) showed small particle size and much better skin permeability. The cumulative amount of total Pyrus serotina var stem extract that penetrated to the skin over time increased over 24 hours in three formulations. The three formulations showed 51.61 ㎍/㎠ (Formulation 0), 75.97 ㎍/㎠ (Formulation 1) and 95.23 ㎍/㎠ (Formulation 2) skin penetration, respectively. Therefore, it was confirmed that the ethanol extracts of Pyrus serotina var stem showed good cosmetic efficacy and excellent epidermis permeation ability when combined with a polymer micelle and cell penetrating peptide. Thus, this extract has the potential to be used as a safe and natural cosmetic material in the future.

• Journal of Korean Physical Therapy Science
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• v.1 no.2
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• pp.223-234
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• 1994

To investigate the affecting factors to the fatigue and subjective symptoms of adult women, the author analyzed the data from 300 women from 3 groups, manufacture workes, clerical workers and service workers, from august 31, 1993 to the September 30, 1993. Followings are the results there from. 1. For the physical symptoms of fatigue, more than 50 % of respondens comiained were "eye strain" with 73.7 %, "malaise" with 67.0 % "went lay down side" with 60.7 %, "yawing" with 60.3 % and "feel sleep" eith 50.3 % in that order. There was no statistically significant difference between labor woker group, but the fatiger rate was highest among office group. For the mental symptoms. There was no symptom over 50 % of responders complained. For the neurotic symptoms, more than 50 % of respondents complained were "backache" with 53.7 %, "headache" with 49.7 % "shoulder pain" with 54.0 % and "unconfortable" with 43.3 %, in that order, "backache" was higest in manufacture group, but the other symptoms were highest among office group. 2. For the most fatigue weekday, most women answered monday with 56.0 % thursday with 16.3 % and friday with 12.0 % in that order, but saturday was 2.0 %, and sunday was 2.05 labor worker group answered monday was the most fatigue day. 3. 37.7 % of respondents answered afternoon was the most fatigue hours, but 22.0 % was answered evening difference among groups. 4. Nothing to do with the general characteristics, such as age, residence, sleep hours, personality, health status, and exercise, and working conditons such as means to attend office, time to attend office, job satisfaction, work hours, and work years, the mean scores of subjective symptoms of fatigue was highest among office group.

• Microbiology and Biotechnology Letters
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• v.43 no.4
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• pp.385-390
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• 2015

In order to develop an eco-friendly biofertilizer, a plant growth promoting rhizobacterium (PGPR), Bacillus sp., SH1RP8 was investigated. SH1RP8 was lyophilized via freeze-drying along with other protective agents that protect cells from lysis. The freezedried powder of Bacillus sp. SH1RP8, containing 5% skim milk (w/v), exhibited the highest survival rate of 30.6% among all the protective agents (skim milk, glucose, and peptone). The lyoprotective effect of the skim milk, mixture including 5% skim milk, and substrates on the survival of the test strain was examined. Control group was added only skim milk and test groups were added skim milk and other substrates. As a result, the group supplemented with both glycerol and 5% skim milk showed the protective effect much higher by 214.29% than the control group. Freeze-dried Bacillus sp. SH1RP8 could be a good candidate as a potential biofertilizer due to its effective PGPR activity.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.111-119
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• 2011

This study was designed to provide basic data applicable to fire investigation through consideration of combustion products and propose vulnerability of combustibles through analysis of $CO_2$ emission. In order to achieve these research objectives, characteristics of combustion products such as smoke release rate of each part(raw leaves, branches and barks), $CO_2$ emission and ash production were considered targeting on 6 oak species(Quercus variabilis Blume, Quercus aliena Blume, Quercus serrata, Quercus mongolica Fisch, Quercus dentata Sapling and Quercus acutissima) using cone calorimeter and smoke density tester. As a result, it was found that raw leaves release smoke more relatively than branches and barks, when they burn, and that Quercus variabilis Blume has the highest smoke density. Also, Quercus acutissima released CO and $CO_2$ which are respectively, 6.67 times and 1.43 times more than Quercus variabilis Blume with low $CO_2$ emission. In addition, branches released CO and $CO_2$ more relatively. There was a big difference in ash production among raw leaves(3.1 g), branches(10.5 g) and barks(16.43 g). It was identified that Quercus serrata produces ashes which are nearly 9.95 times more than Quercus variabilis Blume. It demonstrates that Quercus serrata contains relatively higher minerals and that Quercus variabilis Blume can leave lots of traces like stain and carbonization, as it releases smoke a lot and it's difficult to predict visibility, when a forest fire breaks out in its community area. It is also considered that smoke particles containing oil in the air leave strain on the surface of a tree, and that CO and $CO_2$ emission increases, when crown fire to burn branches breaks out.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.1
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• pp.67-75
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• 2013

The flow stress of zircaloy-4 used in the spacer grid supporting a nuclear fuel rod was determined by the Johnson-Cook model, and model parameters were determined using reverse engineering. Parameters such as A, B, n and $\dot{\varepsilon}_0$ were determined by the tensile test result. To obtain the parameters C and m, a slot milling test and numerical simulation were performed. The objective functions were defined as the difference between the experimental and the simulation results, and then, the parameters were determined by minimizing the objective function. To verify the validity of the determined parameters, cross-verification for each case was conducted through a shearing test and simulation. The results tend to show agreement with the experimental results, such as the features of sheared edges and maximum punch force, with the correlation coefficients exceeding at least 0.97.