• International Journal of Highway Engineering
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• v.7 no.4 s.26
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• pp.113-123
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• 2005

In this study, calcium chloride$(CaCl_2)$, sodium chloride (NaCl), organic acids-containing deicer(NS 40, NS 100), mixed deicier$(NaCl\;70%+CaCl_2\;30%,\;NS\;40\;70%+CaCl_2\;30%,\;NaCl\;70%+NS\;40\;30%,\;NS\;40\;70%+NaCl\;30%)$ is investigated based on the laboratory test for deicing performance, freez-thaw resistance of concrete, and corrosion rate of metal. Test items for deicing performance were ice melting and ice penetration, freezing point depressions and eutectic point, pH, thermal properties for selected deicing chemicals as well as their compatibility with concrete and metal were experimentally investigated. As a test results, in case of the use chloride-containing deicier in area that concrete structures has subjected to freez-thaw reaction in winter season, it showed that mixed deicing chemicals with optimum ratio has desirable method than use one deicing chemicals when is consider to deicing performance and effects, corrosion of steel materials, and freez-thaw resistance of concrete. When use various deicing chemicals mixed, NS40(70%)+calcium chloride(30%) showed the best effective method.

• Journal of the Korean earth science society
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• v.18 no.6
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• pp.515-521
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• 1997

To investigate the nature of the waste materials in the Nanjido Landfill, we have conducted multivariate statistical analysis of geophysical data set comprised of magnetic, gravity, LandSat TM thermal band and surface depression measurement data. Because these data sets show different responses to the depth, we have transformed the observed total field magnetic data and gravity data to the residual reduced-to-pole(RTP) magnetic anomalies and the three dimensional density anomalies, respectively, and utilized the informations about the upper shallow part of the landfills only in the following process. For the statistical analysis at the points of depression measurement, the magnetic, density and LandSat data values at these points are determined by interpolation process. Since the multivarite statistical analysis technique utilizes a clustering algorithm for classification of data set and we have measured the dissimilarity between objects by using Euclidean distance, standardization was applied prior to distance calculation in order to eliminate any scaling effects due to different measurement unit of each data set. The hierarchial grouping technique was used to construct the dendrogram. The optimum number of statistical groups(clusters), which are classified on the basis of geophysical and geotechnical characteristics, appeared to be six on the resulting dendrogram. The result of this study suggests that the dimension and nature of the multicomponent waste landfills can be identified by application of the multivarite statistical analysis technique to integrated geophysical data sets.

• Journal of Preventive Medicine and Public Health
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• v.26 no.1 s.41
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• pp.147-164
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• 1993

A study has been conducted on developing questionnaires to serve as on site diagnostic tools for the early detection of neuropsychiatric impairment among workers chronically exposed to low-level organic solvents. Two drafts of tentative questionnaires have been developed as follows; several question items were selected from questionnaires which were administered to workers exposed to organic solvents in previous studios and were grouped into each symptom category based on the presence of its association using Guttman scaling method, then these selected items were reviewed by neuropsychiatry specialists. The final draft of the questionnaire (total symptom score=36) was developed by selecting 33 question items which had more than a 0.88 Guttman coefficient of reproducibility in each symptom category from a pilot study in which these tentative questionnaires were administered to workers manufacturing soles. Three plants using organic solvents and one plant never using organic solvents as a control group were selected to test the reliability and validity of the developed questionnaires. The major organic solvent in the workplace environment detected by a personal air sampler and GC/MSD nab toluene. The concentration of toluene in air from the department using organic solvent was statistically different from that of the department never using organic solvent. The concentration of toluene from almost all of the workplace did not exceed the allowable level. There was no statistically significant difference between the concentration of urinary hippuric acid from the workers of the department using organic solvent and that of the department never using it. Total symptom score of the plant never using organic solvents was 9.8 and those of the three plants using organic solvents were 15.6, 14.7, and 13,7 respectively. In order to evaluate the validity of the questionnaires, the workers from two different departments of the plant in which usage of organic solvents are totally dofferemt were compared. The total symptom score was 17.8 for workers of the department using organic solvent and 13.5 for the department never using organic solvent and scores of each symptom group between exposure and non-exposure group also showed statistically significant difference. The finding that total symptom score of the exposure group increased as the duration of employment increased indirectly suggests the usefulness of the developed questionnaire to assess the health effects of chronic exposure to organic solvents. The correlation coefficient, which was calculated to evaluate the test-retest reliability, was 0.581 (p=0.001). The coefficient of Crohnbach which reflects the internal consistency of the questionnaire was 0.91. In conclusion, the reliabilty of the questionnaire was well maintained over the time lapse between the two administrations of the questionnaire and despite the seasonal difference.

• Ecology and Resilient Infrastructure
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• v.2 no.1
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• pp.22-32
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• 2015

This study investigated the difference in fish community structures in a main channel and an isolated former channel, considering the environmental factors in the Mangyeong River, Korea. Principal component analysis (PCA) with environmental factors showed that former channels were composed of a fine substrate covered by in-stream vegetation, whereas the main channel was covered by a wide range of substrates with a higher dissolved oxygen and conductivity. The result of the hierarchical cluster analysis with species abundance delineated to the four main groups; three abandoned channel groups and one main channel group. Non-metric multidimensional scaling (NMDS) showed that fish community structures of each study site differed from environmental factors: former channel fish communities were positively related to in-stream vegetation cover, whereas main channel fish communities were positively associated with dissolved oxygen and conductivity. The results indicated that channelization, where there was a separation between the former channel and the main channel, had detrimental effects on fish community structures of both the main channel and the abandoned channel in the Mangyeong River. In conclusion, this study suggested that the connectivity between the main channel and abandoned channel were required to enhance both habitat structural diversity and species diversity of the Mangyeong River.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.132-139
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• 2017

A huge amount of de-icing agent is sprayed during winter to promote traffic safety in cold regions, and the quantity of de-icing agent sprayed has increased each year. The main ingredients in commonly used de-icing agents are chlorides, such as calcium chloride($CaCl_2$) and sodium chloride(NaCl). While calcium chloride is mostly used in Korea and sodium chloride is usually used in the U.S. and Japan, all de-icing agents include chloride ions. The chlorides included in sprayed calcium chloride-based de-icing agents have severe adverse effects, including the corrosion of reinforcing steels through salt damage by infiltrating into road structures, reduced structural performance of pavement or damage to bridge structures, and surface scaling, in combination with freezing damage in winter, as well as water pollution. In addition, the deterioration of paved concrete road surface that occurs after the use of calcium chloride-based de-icing agent accelerates the development of visual problems with traffic structures. Therefore, the present study was performed to prepare an environment-friendly liquid de-icing agent through a reaction between waste organic acids and calcium-based by-products, which are industrial by-products, and to analyze the properties of the de-icing agent in order to evaluate its applicability to road facilities.

• Journal of the Korean GEO-environmental Society
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• v.16 no.9
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• pp.23-32
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• 2015

This study examined blast testing measurement data which had been obtained from 97 field sites in Korea to investigate the comprehensive characteristics of rock blasting-induced vibration focusing on the effect of excavation types (tunnel, bench) and rock types. The measurement data was from the testing sites mostly in Kangwon province and Kyungsang province and rock types were granite, gneiss, limestone, sand stone, and shale in the order of number of data. The study indicated that the blasting-induced vibration velocity was affected by the excavation types (tunnel, bench) and bench blasting induced higher velocity than tunnel blasting. In addition, the vibration velocity was also highly affected by the rock types and therefore, it can be concluded that rock types should be considered in the future to estimate a blasting-induced vibration velocity. Furthermore, the pre-existing criteria was compared with the results of this study and the comparison indicated that there was a discernable difference except for tunnel blasting results based on the square root scaling and therefore, further studies and interests, which include the effects of rock strength, joint characteristics, geological formation, excavation type, power type, measurement equipment and method, might be necessarily in relation to the estimation of blasting-induced vibration velocity in rock mass.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.4
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• pp.281-288
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• 2010

In this study, we investigated anti-oxidative effects of Duchesnea indica extracts by using Oxygen Radical Absorbance Capacity (ORAC). The extracts were prepared with 0 %, 30 %, 50 %, 70 % and 100 % aqueous ethanol respectively. The 30 % EtOH D. indica extract showed higher ORAC activity than the other extracts. Therefore, we performed in vitro studies on cytotoxicity of NIH-3T3 cells and MMP-8 collagenase inhibition using by the 30 % EtOH extract. The 30 % EtOH extract showed no cytotoxicity and significant inhibition on MMP-8 collagenase. And we performed clinical studies for the anti-wrinkle effect of the Di-Wrinkle Free Cream. The cream formula was prepared with 2 % arbutin and 1 % D. indica extract. Twenty one healthy women volunteers, ages of 35 and 50, applied the cream on their faces twice a day for 8 weeks. The skin was evaluated with PRIMOS (phaseshift rapid in vivo measuring of human skin) system and analyzed by the student's paired t-test. The wrinkles on the eye region were reduced by 13 % based on the PRIMOS system after 8 weeks. In the safety study of the Di-Wrinkle Free Cream, no symptoms were observed such as erythema, edema, scaling, itching, stinging, burning, tightness and prickling by visual observation and medical examination of volunteers for 8 weeks. Moreover, there was no noticeable skin disorder during experience period. These results suggested that D. indica extracts could be applied as cosmeceuticals effective for anti-wrinkle.

• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.411-421
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• 1993

The purpose of this study was to assess the effect of polycaprolactone strip with minocycline on the periodontal pocket in humans and the various clinical parameters in rapidly progressive periodontitis. Nine patients with rapidly progressive periodontitis were selected for the study. They had not taken antibiotics for 6 months and had no history of dental treatment for 6 months before the study. They were in good general health. By the split-mouth method, patients received a supragingival scaling, experimental group (9sites) were subjected to subgingival placement of polycaprolactone strips(1 strip) containg 30% minocyclne and control group (9 site) were subjected to subgingival placement of not polycaprolactone strips(1 strip) containing 30 A Minocycline. Strips were replaced with freshly filled ones at 1 week and 2 week. All strips were removed from pockets at 3 week Clinical examination (plaque index, gingival index, probing pocket depth) and distribution on the bacteria morphology of subgingival plaque were monitored on baseline (0 week), 1, week, 2 week, 4 week and 8 week. The result were as follows : 1. Plaque index in experimental group was not significantly reduced during all weeks(P<0.05), but slightly reduced at 2, 4 and 8 weeks and that in control group was not significantly reduced during monitoring period. 2. Probing pocket depth was significantly reduced at 2, 4 and 8 weeks(P<0.05) in experimental group, but that in control group was not siginificantly changed during monitoring period. 3. Gingival index was significantly improved at 2, 4 and 8 weeks(P<0.05) in experimental group but that in control group was not significantly changed. 4. Percentage of cocci was significantly increased at 2, 4 and 8 weeks in experimental group but that in control group was not significantly changed. 5. Percentage of non-motile rods in both group were not significantly changed when compared with those of baseline(0 week) (P<0.05). 6. Percentage of motile rods was siginificantly reduced at 1, 2 and 4 weeks in experimental group (p<0.05) but that in control group was not significantly changed. 7. Percentage of spirochetes was siginificantly reduced during all weeks(P<0.05) but that in control group was not significantly changed. The result showed that polycaprolactone containing 30% minocycline effect the clinical index and bacterial morphotype.

• Ecology and Resilient Infrastructure
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• v.1 no.2
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• pp.49-60
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• 2014

Fish assemblages play an integral role in stream ecosystem and are influenced by stream environmental conditions and habitat disturbances. Fish community structures and habitat parameters of U.S. EPA rapid bio-assessment protocol were surveyed to investigate the effect of stream environment and habitat disturbance on fish communities at 13 study sites in the Gapyeong Stream, a typical gravel-bed stream. Principal component analysis (PCA) based on data from habitat assessment at each study site indicated that the study sites were differentiated by habitat parameters such as embeddedness, velocity/depth regime and sediment deposition, which were related with bed slope. A total of 46 species belonging to 12 families were collected in the Gapyeong Stream. A dominant species was Zacco koreanus, subdominant species was Z. platypus. Hierarchical cluster analysis based on species abundance classified fish communities into the three main groups along the stream longitudinal change. Non-metric multidimensional scaling (NMDS) portrayed that fish community structures were related to major habitat parameters, i.e., epifaunal substrate/available cover, embeddedness, velocity/depth regime, sediment deposition, channel alternation and frequency of riffles. These results suggested that fish community structures were primary affected by the longitudinal environmental changes, and those were modified by habitat disturbance in the Gapyeong Stream, a gravel-bed stream.

• Resources Recycling
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• v.6 no.2
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• pp.22-28
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• 1997

In recent yean thc problem of wastc plastics arc greatly incrcascd with ihe result uf lndushial growth. As a rcsult the amount of wastc plaslics in domestic area is appraxhnately 2,300,000 t<~nin 1996 base and contmuously increasing more than 12% cvcry ycar. Thc disposal way of these waste plastics arc dlLl malnly rely~ng on landill1 or partially incinuralion So that it hss become a senous social problem due to the second envirnmentd pollution. The tcchnologics iar prducing oil from the waste plastics have hccn dcvelopcd far along pennd and currently some of them are in a commercialiration stage Pyrolysis process in one of the major process m heating waslc plaslics bul still has some restlichons for the cammcrc~dizatian duc lo 11s emnom~cal problems assaciated with a systcmiltlc lecd collcctionidispnsJ ways. Cansldenng cnvaomcnld problems, thc inclease m the charge for waste matcds trcatmcnt and thc lmlitarion ni disposal area, it is inteicstcd that the wastc plastics treabncnt by pyrolysn. which would be the safest and the most eilic~ent process for cnnvcrting fecd wastc to rc-usablc rcsourccs. would he predomhant m ihe near h~lurc Thc shldy aims inr the development of haslc ted~nolagy for scaling up to a com~nercial sire through pyrolys~s process which is cnnduclcd under the absence of air. Furthern~orc the waste plastics can be recycled as iual gas or oil wilhout harmful effects in enviroment, The waste w e d plastics arc pyrolyzed in (he fluidized bcd rcaclor under continuous way and thc ail ylcld gives approx~marcly 47 4%.