• Analytical Science and Technology
• /
• v.19 no.1
• /
• pp.96-102
• /
• 2006

Trimethylamine (TMA) is one of the difficult odorous compounds for the collection and analysis. Although sulfuric acid absorption and/or sulfuric acid impregnated filter method are commonly recommended for its sampling, these methods also suffer from difficulties involved in sample treatment and operational procedures. Hence, as an ancillary approach to measure TMA, we investigated the combination of bag sampling and SPME analysis for TMA measurements. For the purpose of our study, we investigated the following three subjects: 1) temporal variability of standard storage, 2) bag loss effect of TMS, and 3) TMA loss due to repetitive analysis of an identical bag sample. According to our storage test up to 7 or 20 dyas, TMA loss were found to occur up to 40 to 50% within relatively short period of up to 48 hrs depending on its concentration ranges. When the tests were made for bag loss by transferring TMA standards across different size bags, we were able to find that the extent of bag loss are not significant with 5 to 20% loss rate. Finally, the TMA sorptive loss via its exposure to SPME fiber was generally estimated to run from 2 to 3%.

• Corrosion Science and Technology
• /
• v.12 no.2
• /
• pp.65-78
• /
• 2013

The present investigation deals with the corrosion inhibition of mild steel in 1M $H_2SO_4$ with 1, 4-dihydro pyridine and its derivatives prepared using microwave activation method. The synthesis of inhibitor was confirmed by IR spectra. The effect of 1, 4-dihydropyridine derivatives on the corrosion inhibition of mild steel in 1M $H_2SO_4$ was studied using weight loss and electrochemical polarization techniques. Influence of temperature (303-333K) and synergistic effect of halide ions ($I^-$, $Br^-$ and $Cl^-$) on the inhibition behaviour was also studied. Corrosion products on the metal surface were analyzed by scanning electron microscopy (SEM) and a possible mechanism of inhibition by the compounds is suggested. Thermodynamic parameters were calculated using weight loss data in order to elaborate the mechanism of corrosion inhibition. Polarization measurements revealed that the studied compounds acted as mixed type inhibitor but slightly anodic in nature. Electrochemical impedance measurements revealed that the compounds were adsorbed onto the carbon steel surface and the adsorption obeyed the Langmuir adsorption isotherm. The synergistic effect of halide ions on the IE increases with increase in concentration. The IE obtained from atomic absorption spectrophotometric studies was found to be in good agreement with that obtained from the conventional weight loss method. SEM revealed the information of a smooth, dense protective layer in presence of the inhibitors.

• Journal of Korean Academy of Nursing
• /
• v.30 no.4
• /
• pp.917-931
• /
• 2000

This study was to provide understanding for the juvenile problem of drug brought about by industrialization, and the importance people that we should take a role in helping to resolve the problem. The purpose of this study lies in approaching the effective methods to prevent Korean adolescents from being involved in drug by examining the factors of their experience. The method of this study is designed to grasp the adolescents' drug experience, its meaning, its structure and the nursing intervention ways. By applying a phenomenological approach which is based on a qualitative research method, the researchers hoped to reveal key data in each group. It has been carried on from October 1998 until September 1999 with sample of 5 adolescent inmates in K mental hospital located in Seoul. The data were collected by sereous personal deep interviews and observations. Collected data were analyzed according to the phenomenological method suggested by Giorgi. The results of this study are as follows: First, pleasure seeking: curiosity, joy, and fun; Second, affiliation: formation of clique with the same age; Third, escape from reality: loneliness, emptiness, heroic mind, self- confidence, self-absorption, and comfort; Forth, feeble- mindedness: anxiety, fear, and temptation; Fifth, psychological unadaptation: wandering, forfeiture, and incompetence; Sixth, physical counteraction: headache, vomiting, loss of memory, loss of appetite and loss of sensibility; Seventh, psychological confusion: illusion, auditory hallucination and dream; Eighth, recovery of self-consciousness: repentance, desire and awareness This study results in the following suggestions of the nursing intervention 1. To cultivate a wholesome game culture for the adolescents. 2. To make up the group activities so that the adolescents can establish their sense of identity through a variety of group counseling program. 3. To foster the capability to cope with the change in the process of social accommodation. 4. To enforce the social life skill for the adolescents. 5. To practice the systematic education about drug use. 6. To develop the social education programs. 7. To help the adolescents build up their sense of identity by applying the adolescent cure programs. Above all, it is necessary that school and community as well as home should establish the educational environment paying special concern and consideration to the adolescents.

• Journal of Nutrition and Health
• /
• v.39 no.1
• /
• pp.11-17
• /
• 2006

The effect of the level of casein phosphopeptide (CPP) on mineral (Ca and P) bioavailabilties and bone biomarker of aged ovariectomized (OVX) Sprague-Dawley rats were studied as a model for postmenopausal bone loss. Forty five Spargue dawley rats, 220-230 g of body weight were fed a control diet (AIN 93M) or containing different level of CPP diet for 7 weeks: $0\%$ (sham control; SC, OVX control; OC), $1\%$ (OVX low CPP diet: OL), $2\%$ (OVX medium CPP diet; OM), $3\%$ (OVX high CPP diet; OH) Ca absorption was unaffected by increasing CPP content from 0 to $3\%$. Urinary Ca excretion was increased by OVX, and decreased by CPP significantly (p < 0.05) with no evident doserelationship. The urinary P excretion was increased by CPP intake in OVX rats. The fecal excretion of P given CPP decreased in OVX with dose dependent manner. Ca and P contents of femur significantly increased by adding 2 or $3\%$ of CPP when compared with OC group and OL group (p < 0.05). There were no significant differences in serum alkaline phosphatase activity and c-terminal telopeptide excretion in experimental groups. Although ovariectomy induced the increase in urinary c-terminal telopeptide excretion, 2 or $3\%$ of CPP in the diet decreased urinary c-terminal telopetide excretion significantly. These finding suggest the usefulness of CPP in the prevention of postmenopausal bone loss by decreasing urinary Ca excretion and bone resorption. Over 2 percent of CPP in the diet was effective to prevent postmenopausal bone loss.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.20 no.12
• /
• pp.1139-1146
• /
• 2010

The indoor noise of the naval vessel is very important related to the optimum environmental conditions for crews as well as the ability of fighting power of antisubmarine. Especially, sonar equipment room is one of the rooms where require to be silent because the informations of the underwater noise are collected and analyzed in there. In this paper, the sound reduction of the TASS console, one of the main noise sources in a sonar equipment room for a typical naval vessel, is described. The noise source of this TASS console is the flowing noise of cooling fan. In order to reduce this kind of noise, the plenum chamber and acoustic elbow were developed. Related to the development of the plenum chamber, the area of the air-outlet and sound absorption of the inner lining were investigated experimentally with the evaluation system of the sound insertion loss. Acoustic elbow was also manufactured and evaluated with the evaluation system of the sound insertion loss. Finally, in order to evaluated the ability of noise reduction of the plenum chamber and acoustic elbow, the indoor noise of the sonar equipment was measured when they were appled to TASS console.

• Korean Journal of Materials Research
• /
• v.9 no.9
• /
• pp.913-918
• /
• 1999

As an alternative evaluation method of electromagnetic shielding properties, the material parameters are considered in determining the qualitative value of shielding effectiveness. The specimens are metallized nylon fabrics with the thickness of about 0.1 mm and the electrical conductivities in the range from 6.4$\times$10~2.4$\times$10(sup)5 mhos/m. On the basis of shielding theory, the shielding effectiveness (which is a sum of reflection loss and absorption loss) has been determined from the material parameters of the barrier sheets. For the conductive fabrics, the dominant shield mechanism is predicted to be reflection loss, which shows an increasing function of electrical conductivity. Comparing these theoretical value with the directly measured surface impedances, the error range is found to be within 10 dB, which demonstrates that the proposed material-parameters method can be a convenient way to determine the electromagnetic shielding properties.

• The Korean Journal of Ecology
• /
• v.3 no.1_2
• /
• pp.31-39
• /
• 1980

Light energy utilization was investigated in the fallen stems of Opuntia bigelovii. Threshold time for the decreasing steady state of acid accumulation in the palisade tissue of Opuntia stems was 4 hours under 1,000 $\mu Em^{-2}sec^{-1}$ of PAR at $75^{\circ}C$, while stomatal closing throughout the stem stage was illustrated by 256.0-310.4 sec $\textrm{cm}^{-1}$ of stem diffusive resistance and 0.20g $day^{-1}$ of the water loss rate as cuticular resistance. The acid loss rate in the stems per 4 hours was related to tissue water contents and a few acid loss rate could be recognized at the water content rage of 56.4%~46.8%. Endogenous oscillation of tissue acidity due to the diurnal rhythmic phenomena depended on the tissue water content was found in the Opuntia stems with stomatal closing during the normal day/night cycle. The survival rate of 1 segment to survive 2 years old cactus was 22.7% in desert environments. Such a compensation photosynthesis which utilizes light energy and maintains the reassimilation of endogenous gases was interpreted as conceptual model.

• Korean Journal of Optics and Photonics
• /
• v.3 no.4
• /
• pp.258-265
• /
• 1992

A low loss optical waveguide of $P_{2}O_{5}-SiO_{2}$on Si substrate is produced by using the chemical vapour deposition method of $SiO_2$ thin films used in Si technology. Propagation loss of the waveguide layer was 1.65 dB/cm as produced and reduced down to 0.1 dB/cm after heat treatment at $1100^{\circ}C$. By using laser lithography and reactive ion etching method $P_{2}O_{5}-SiO_{2}$ waveguide was produced and subsequently annealed at $1100^{\circ}C$.As a result of this annealing the shape of the waveguide core was changed from rectangular to semi-circular form, and the propagation loss was reduced as down to 0.03 dB/cm at 0.6328$\mu$m and 0.04dB/cm at 1.53$\mu$m. We think that the mechanism of the reduction in propagation loss during the heat treatment is the following: 1) The hydrogen bonding in waveguide layer, which causes absorption loss, is dissociated and diffused out. 2) The roughness of the interface and the micro-structure of the waveguide layer is removed. 3) The irregularities in the cross-sectional shape of the waveguide which was induced during the lithographic process were disappeared by flowing of the waveguide core.

• The Journal of the Korean Society for Microbiology
• /
• v.35 no.3
• /
• pp.203-214
• /
• 2000

Porphyromonas gingivalis has been implicated in periodontal diseases. Accumulating evidence suggests that cardiovascular disease is the most prevalent medical problem in patients with periodontal diseases. In order to check the possibility that P. gingivalis is involved in coronary heart disease, the present study was performed to observe P. gingivalis adherence and invasion of human coronary artery endothelial cells (HCAEC) and production of cytokines and growth factors by HCAEC upon P. gingivalis infection. $^3H$-labeled P. gingivalis 381 was incubated with HCAEC for 90 min. The radioactivity of the washed HCAEC was a measure of the absorbed (adhering and invading) P. gingivalis. The absorption radioactivity of the HCAEC infected by P. gingivalis was determined to be 59.58% of the input bacterial cells. In contrast, the absorption radioactivity of the cells infected by S. gordonii Challis which was employed as a control was negligible (0.59%). DPG3, a P. gingivalis mutant defective of fimbriae, appeared to be impaired to some extent in capability of adherence/invasion as compared to that of the parental strain 381, showing 43.04% of the absorption radioactivity. The absorption radioactivity of the HCAEC infected by P. gingivalis 381 in the presence of excessive fimbriae at the concentrations of $50\;{\mu}g$ and $100\;{\mu}g/ml$ was 57.27 and 45.44%, respectively. Invasion of HCAEC by P. gingivalis 381 was observed by an antibiotic (metronidazole) protection assay and transmission electron microscopy (TEM). In the antibiotic protection assay, invasion by the bacterium was measured to be 0.73, 1.09, and 1.51% of the input bacterial cells after incubation for 30, 60, and 90 min, respectively. Invasion by DPG3 was shown to be 0.16% after 90-min incubation. In comparison of invasion efficiency at 90 min of the incubation, the invasion efficiency of DPG3 was 0.37% while that of its parental strain 381 was 2.54%. The immunoblot analysis revealed fimbriae of P. gingivalis did not interact with the surface of HCAEC. These results suggest that fimbriae are not the major contribution to the adherence of P. gingivalis to HCAEC but may be important in the invasion of HCAEC by the bacterium. The presence of cytochalasin D ($1\;{\mu}g/ml$) and staurosporine ($1\;{\mu}M$) reduced the invasion of HCAEC by P. gingivalis 381 by 78.86 and 53.76%, respectively, indicating that cytoskeletal rearrangement and protein kinase of HCAEC are essential for the invasion. Infection of P. gingivalis induced HCAEC to increase the production of TNF-${\alpha}$. by 60.6%. At 90 min of the incubation, the HCAEC infected with P. gingivalis cells was apparently atypical in the shape, showing loss of the nuclear membrane and subcellular organelles. The overall results suggest that P. gingivalis may cause coronary heart disease by adhering to and invading endothelial cells, and subsequently damaging the cells.

• Corrosion Science and Technology
• /
• v.8 no.2
• /
• pp.45-52
• /
• 2009

The corrosive behavior of mild steel in 0.05 M to 10 M $H_2SO_4$ solutions containing different concentrations of tetrahydropyrimidine derivatives (THPM) was investigated using weight loss method, gasometric technique, electrochemical studies which include AC - impedance and potentiodynamic polarization method, atomic absorption studies and synergistic effect. The results obtained reveal that THPM derivatives is an efficient mixed type inhibitor but slightly anodic and it is more effective in reducing corrosion of mild steel in $H_2SO_4$ media. The adsorption of the inhibitor on the mild steel surface obeys the Langmuir adsorption isotherm. The thermodynamic parameters of adsorption reveal a strong interaction and spontaneous adsorption of THPM on the mild steel surface. The influence of temperature and inhibitor concentration on the corrosion of mild steel has also been investigated.