• Journal of the Korean Home Economics Association
• /
• v.40 no.11
• /
• pp.193-205
• /
• 2002

To evaluate farmers' workload during harvesting grapes in summer, this study investigated farmers' physiological, psychological responses, work postures and thermal environment around in the field. This field study was conducted in the Anseong County of Kyonggi Province at the end of August. Five career farmers (1 male, 4 females) volunteered as subjects. Three of them were over their sixties. During harvesting grapes in the field, physiological responses were monitored continuously. 1. Air temperature (T/sub a/), air humidity(H/sub a/), black globe temperature(T/sub g/), air velocity and WBGT around the grape field were 26.9℃, 77.7%RH, 32.8℃, 0.08㎧ and 26.3℃, respectively. Because farmers started the harvesting task in early morning, thermal environments weren't conditions to give farmers severe heat strain. 2. The percentage of the work postures was larger in order of standing, walking, and bending one's back posture. Particularly, the percentage of standing posture with raising both arms above shoulder of two farmers was up to 29% and 61% of the total work duration. 3. Rectal temperature (T/sub re/), mean skin temperature (T/sub sk/), clothing microclimate temperature (T/sub cl/) on the chest and the back, heart rate (HR) and energy expenditure (EE) were 37.2℃, 33.1℃, 32.0℃, 32.4℃, 88bpm and 1.3 Kca1/㎡/min respectively. In the point of these physiological results, we evaluated that the harvesting task was a moderate work. 4. All farmers expressed‘hard, hot, humid and slightly uncomfortable’ at the end of works for each subjective questionnaire. The grape harvesting tasks were not evaluated as a very hard work in the point of physiological work standards. But we considered 1) inappropriate work posture (standing posture with raising both arms above shoulder) and 2) farmers' age as burden factors. These findings suggest that adding adequate protective clothing/equipments for farmers may contribute to maintain their body temperature within the normal range, stabilize HR and decrease psychological strain.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.28 no.5
• /
• pp.713-722
• /
• 2004

This study examined the effects of two kinds of functional sun hats through a head-manikin test and a climatic chamber trial for farm workers in summer. Experiment was composed of four conditions. The first condition was the condition without any hat (Control). The second was the condition with a sun hat on the market (Hat A). The third was the condition with a functional sun hat made of reflective fabric (Hat B). The last was the condition with a functional sun hat having a ventilating structure as well as reflective fabric (Hat C). For the subjects in the climatic chamber trials, 12 healthy males volunteered. Air temperature, relative humidity and globe temperature in the chamber was maintained at $33{\pm}0.5^{\circ}C,\;65{\pm}5%RH\;and\;39{\pm}1^{\circ}C\;(WBGT\;33^{\circ}C)$. Subjects did a simulated red pepper-work (50-min work and 10-min rest, twice repetition) for 120 min. As the result of head-manikin test, the surface temperature on middle of back-neck was the lowest in Hat B of four conditions and the surface temperature on top of head was the lowest in Hat C. As the result of climatic chamber trials, there were apparent differences between with (Hat A, Hat B, Hat C) and without a sun hat (Control). In rectal temperature ($T_{re}$), mean skin temperature ($\={T}_{sk}$), heart rate (HR), total sweat rate (TSR), The physiological heat strain was less in the condition with hats than in the condition without a sun hat. As the increasing rate in Tre, Hat B is the most effective hat for alleviation heat strain. As the subjective responses, Hat B was the most effective hat for thermal comfort even though the difference was not significant. Hat C was less effective than Hat B and the reason might be the increase of weight due to inserting the ventilating structure.

• Journal of Microbiology and Biotechnology
• /
• v.5 no.2
• /
• pp.68-73
• /
• 1995

Pseudomonas sp. P20 was shown to be capable of degrading biphenyl and 4-chlorobiphenyl (4CB) to produce the corresponding benzoic acids wnich were not further degraded. But the potential of the strain for biodegradation of 4CB was shown to be excellent. The pcbA, B, C and D genes responsible for the aromatic ring-cleavage of biphenyl and 4CB degradation were cloned from the chromosomal DNA of the strain. In this study, the pebC and D genes specifying degradation of 2, 3-dihydroxybiphenyl (2, 3-DHBP) produced from biphenyl by the pebAB-encoded enzymes were cloned by using pBluescript SK(＋) as a vector. From the pCK102 (9.3 kb) containing pebC and D genes, pCK1022 inserted with a EcoRI-HindIII DNA fragment (4.1 kb) carrying pebC and D and a pCK1092 inserted with EcoRI-XbaI fragment (1.95 kb) carrying pebC were constructed. The expression of pcbC and D' in E. coli CK102 and pebC in E. coli CK1092 was examined by gas chromatography and UV-vis spectrophotometry. 2.3-dihydroxybiphenyl was readily degraded to produce meta-cleavage product (MCP) by E. coli CK102 after incubation for 10 min, and then only benzoic acid(BA) was detected in the 24-h old culture. The MCP was detected in E. coli CK1022 containing pebC and 0 genes (by the resting cells assay) for up to 3 h after incubation and then diminished completely in 8 h, whereas the MCP accumulated in the E. coli CK1092 culture even after 6 h of incubation. The 2, 3-DHBP dioxygenases (product of pebC gene) produced by E. coli CK1, CK102, CK1023, and CK1092 strains were measured by native PAGE analysis to be about 250 kDa in molecular weight, which were about same as those of Pseudomonas sp. DJ-12, P. pseudoa1caligenes KF707, and P. putida OU83.

• Journal of Microbiology
• /
• v.34 no.4
• /
• pp.341-348
• /
• 1996

The regulation of xylE gene expression was examined by using vector promoter and construction of genetically engineered microorganisms (GEMs) for application in microcosm. When the xylE gene wsa subcloned into pBluscript SK(+) under the control of lac promoter (pTY1) in E. coli, and the expression was induced by IPTG, the enzyme activity of catechol 2, 3-dioxygenase was increased 4.7 times more than that of the crude extracts from transformants harboring pTY1. We suggest that the xylE gene has its own promoter at the upstream portion, because it was able to be expressed even in the absence of IPTG. A recombinant plasmid, pSW3a harboring the xylE gene under the T7 promotor, showed the activity of 14.5 units/mg protein, higher than that of parental strain, E. coli PYT1. The xylE gene in recombinant plasmid pSW3a was used as reporter gene for the application in microcosm ecosystem, since it was used for detection of xylE-positive clones by catechol spray on the agar plates. The pSW3a in E. coli was introduced into Pseudomonas patida to construct GEM strain, and examined for the exxpression and functional stability in microcosms.

• Korean Journal of Microbiology
• /
• v.30 no.1
• /
• pp.1-7
• /
• 1992

We cloned a gene cluster encoding phenanthrene-degrading enzymes on a 6.8-kb Xhol fragment from the Pseudomonas sp. DJ77 chromosomal DNA into the vector pBLUESCRIPT SIC(+). The resultant clone, containing the recombinant plilsmid pHENX7, was able to convert 3-methylcatechol to a yellow mela-cleavage compound. Since the pHENX7R in which the DNA insert was cloned in the opposite orientation lacked extradiol dioxygenase activity. the direction of transcription was established. Four polypeptides, PhnC (24 kDa). PhnD (31 kDa), PhnE (34 kDa). and PhnF (15 kDa), were identified in E coli JM101 transformed with several pHENX7-derived plasmids. The locations and extents of ~ndividual genes were determined by subcloning. The gene order was phnC-phnD-phnE-phnF-phnG, and phnC, phnD, phnE, and phnG genes encoded glutathione S-transferase, mrta-cleavage compound hydrolase, extradiol dioxygenase, mera-cleavage compound dehydrogenase, respectively.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.358-358
• /
• 2010

Ion beam bombardment at low energy forms nanosize patterns such as ripples, dots or wrinkles on the surface of polymers in ambient temperature and pressure. It has been known that the ion beam can alter the polymer surface that induces skins stiffer or the density higher by higher compressive stress or strain energies associated with chain scissions and crosslinks of the polymer. Atomic scale structure evolution in polymers is essential to understand a stress generation mechanism during the ion beam bombardment, which governs the nanoscale surface structure evolution. In this work, Molecular Dynamics (MD) simulations are employed to characterize the phenomenon occurred in bombardment between the ion beam and polymers that forms nanosize patterns. We investigate the structure evolution of Low Density Polyethylene (LDPE) at 300 K as the polymer is bombarded with Argon ions having various kinetic energies ranging from 100 eV to 1 KeV with 50 eV intervals having the fluence of $1.45\;{\times}\;1014 #/cm2$. These simulations use the Reactive Force Field (ReaxFF), which can mimic chemical covalent bonds and includes van der Waals potentials for describing the intermolecular interactions. The results show the details of the structural evolution of LDPE by the low energy Ar ion bombardment. Analyses through kinetic and potential energy, number of crosslinks and chain scissions, level of local densification and motions of atoms support that the residual strain energies on the surface is strongly associated with the number of crosslinks or scissored chains. Also, we could find an optimal Ar ion beam energy to make crosslinks well.

• Structural Engineering and Mechanics
• /
• v.89 no.1
• /
• pp.23-31
• /
• 2024

Ratcheting is the cyclic buildup of inelastic strain on a structure resulting from a combination of primary and secondary cyclic stress. It can lead to excessive plastic deformation, incremental collapse, or fatigue. Ratcheting has been numerically investigated on a cantilever beam, considering the current study's primary and secondary bending loads. In addition, the effect of input frequency on the onset of ratcheting has been investigated. The non-linear dynamic elastic-plastic approach has been utilized. Analogous to Yamashita's bending-bending ratchet diagram, a non-dimensional ratchet diagram with a frequency effect is proposed. The result presents that the secondary stress values fall sequentially with the increase of primary stress values. Moreover, a displacement amplification factor graph is also established to explain the effect of frequency on ratchet occurrence conditions. In terms of frequency effect, it has been observed that the lower frequency (0.25 times the natural frequency) was more detrimental for ratchet occurrence conditions than the higher frequency (2 times the natural frequency) due to the effect of dynamic displacement. Finally, the effect of material modeling of ratcheting behavior on a beam is shown using different hardening coefficients of kinematic hardening material modeling.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.3
• /
• pp.450-456
• /
• 2006

Pseudomonas fluorescens MC07 is a growth-promoting rhizobacterium that suppresses mycelial growth in fungi such as Rhizoctonia solani, Pythium ultimum, Fusarium oxysporum, and Phytophthora capsici. To determine the role of the bacterium's antifungal activity in disease suppression, we screened 2,500 colonies generated by Tn5lacZ insertions, and isolated a mutant 157 that had lost antifungal activity. The EcoRI fragment carrying Tn5lacZ was cloned into pBluescript II SK(+) and used as a probe to isolate wild-type clones from a genomic library of the parent strain, MC07. Two overlapping cosmid clones, pEH4 and pEH5, that had hybridized with the mutant clone were isolated. pEH4 conferred antifungal activity to the heterologous host P.fluorescens strain 1855.344, whereas pEH5 did not. Through transposon mutagenesis of pEH4 and complementation analyses, we delineated the 14.7-kb DNA region that is responsible for the biosynthesis of an antifungal compound. DNA sequence analysis of the region identified 11 possible open reading frames (ORF), ORF1 through ORF11. A BLAST search of each putative protein implied that the proteins may be involved in an antifungal activity similar to polyketides.

• Korean Journal of Pharmacognosy
• /
• v.34 no.1 s.132
• /
• pp.80-85
• /
• 2003

Water extract from Astragali Radix (AR) was tested for the safety using Ames, Bacillus subtilis Rec, and umu gene expression mutagenicity tests. Mutagenic activity in any assays we tested was not found. In Ames test, Salmonella typhimurium TA98 and TA 100 were used to identify mutagenic property, and the number of histidine revertants was measured. In the Recassay, Bacillus subtilis ${H-17(Rec^+)\;and\;M-45(Rec^-)}$ strains were used to test DNA damage activity. In the SOS umu test, Salmonella typhimurium TA1535 containing plasmid pSK1002 was used as a test strain, and we monitored the levels of umu operon expression by measuring the ${\beta}-galactosidase$ activity. From the results, there was no DNA damage and mutagenicity of AR. Hepatotoxicity of AR to female ICR mice was also monitored by the measurements of s-GOT, s-GPT, LDH activities after oral feeding for 15 days. AR was not shown any significant changes of s-GOT, s-GPT and LDH activities in mice sera.

• Journal of Life Science
• /
• v.14 no.5
• /
• pp.815-820
• /
• 2004

A bacterum containing antitumor activity was isolated from traditional korean food, Jeotgal. Through the 16s rRNA sequence analysis, the bacterium was identitied as a strain of Bacillus subtilis SW-l. The best culture condition for antitumor activity of the bacterium is 3% of soluble starch and 1 % of yeast extract as corbon and nitrogen sources, respectively. Cytotoxicitic concentrations of the culture supernatant of B. subtilis SW-1 against cancer cell lines, A549 and SK-OV3 were 30 ul/ml and 40 ul/ml, respectively, as $IC_{50}$/ values. In DNA fragmentation assay, the culture supernatant showed the programmed cell death (apoptosis) to cause degrading the chromosomal DNA like ladder. Taken together, the culture supernatant of the B. subtilis SW-1 has some possibility to be used as an antitumor agent.