• Economic and Environmental Geology
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• v.22 no.1
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• pp.35-63
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• 1989

Geochemical characteristics of the Guryongsan (Ogcheon) uraniferous black slate show that this is an analogue to the conventional Chattanooga and Alum shales in occurrences. Whereas, its highest enrichment ratio in metals including uranium, among others, is explained by the cyclic sedimentation of the black muds and quartz-rich silts, and the uniform depositional condition with some what higher pH condition compared to the conditions of the known occurrences. The cyclic sedimentation, caused by the periodic open and close of the silled basin, has brought about the flush-out) of the uranium depleted water and the recharge with the new metal-rich sea water, which consequently contributed to the high concentration of metals in mud. The metal-rich marine black muds, which mostly occur in the early to middle Palaeozoic times, is attributed by the geologic conditions which related to the atmospheric oxygen contents, and these are scarcely met in the late Precambrian and/or with the onset of Palaeozoic era in the geologic evolution of the earth.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.457-473
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• 2023

Asbestos has been produced, imported and used in various industries in Korea over the past decades. Since asbestos causes fatal diseases such as malignant mesothelioma and lung cancer, the use of asbestos has been generally banned in Korea since 2009. However, there are still many asbestos-containing materials around us, and safe management is urgently needed. This study aims to examine asbestos-related trend changes using major asbestos-related keywords based on the asbestos trend analysis using big data for the past 32 years (1991 to 2022) in Korea. In addition, we reviewed both domestic trends related to the production, import, and use of asbestos before 1990 and asbestos-related policies from 2023 to 2027. From 1991 to 2000, main keywords related to asbestos were research, workers, carcinogens, and the environment because the carcinogenicity of asbestos was highlighted due to domestic production, import, and use of asbestos. From 2001 to 2010, the main keywords related to asbestos were lung cancer, litigation, carcinogens, exposure, and companies because lawsuits were initiated in the US and Japan in relation to carcinogenicity due to asbestos. From 2011 to 2020, the high ranking keywords related to asbestos were carcinogen, baseball field, school, slate, building, and abandoned asbestos mine due to the seriousness of the asbestos problem in Korea. From 2021 to present (2023), the main search keywords related to asbestos such as school, slate (asbestos cement), buildings, landscape stone, environmental impact assessment, apartment, and cement appeared.

• Journal of Korean society of Dental Hygiene
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• v.2 no.1
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• pp.85-95
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• 2002

The purpose of this study was to examine dental hygienists' knowledge of implant operation, which is recently emerging as one of the important medical services in the dental treatment sector. It's ultimately intended to serve as a basis for the preparation of more effective, appropriate implant-education programs for dental hygienists and to help them, who take a crucial part in implant operation, provide better dental services to patients who are in need of implant operation. The subjects in this study were 368 selected dental hygienists who were working in the dental institutions in the region of Taegu. The results of this study were as below: 1. The largest number of the dental hygienists investigated, 34.1%, were at age 25 to 27. The second most common age was 24 and under, and the third most common age group was 28 to 30. For educational level, most of them, 91.0%, were junior-college graduates, and 9.0% were being in or graduated from four-year-course university. Concerning career, 52.7%, the greatest percentage, had worked for one to three years, and 41.3% had a four-year or higher career. 812%, most of them, were working in dental clinics, and 18.3% were serving in dental hospital or general hospital. 2. Many of the dental institutions were providing implant operation services, as the dental institutions where 64.9% of the subjects were working conducted implant operation. In relation to the necessity of implant operation, the dominant opinion, 73.0%, was thai it's needed to make oral slate healthier. So there was a strong tendency to ad mit implant as one of the necessary treatments in the dental treatment sector. 3. Their collective mean implant knowledge got $57.02{\pm}14.11$. And the collective average of 21 items was $2.7153{\pm}0.6720$ on the basis of 5 points, which was below the average(3 points of Likert scale). This meant that the dental hygienists didn't have a good knowledge or understanding of implant. When it's taken into account what role should be performed by dental hygienists, their implant knowledge should be increased. 4. As a result of examining the effect of the general characteristics on their implant knowledge, the educational level(t=-3.481, P=0.001) and the type of dental institution where they were working(F=16.476, P=0.001) made a significant difference. 5. Their implant knowledge was significantly different according to whether or not the dental institution they were serving conducted implant operation (t=7.199, P=0.001). And, whether or not they agreed to the necessity of implant operation also generated a significant difference to their implant knowledge(F=8.610, P=0.000).

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.7
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• pp.5029-5037
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• 2015

The objective of this study is to investigate the distribution of asbestos containing materials and to evaluate risk assessment method in some schools, Korea. For the survey on ACM risk assessment, we used both EPA AHERA rule and ASTM rule. We investigated 100 schools between January and December in 2010. Detection rate of the ACM according to construction year showed that before 1980's, 1990's, 2000's, after 2000's buildings were 100%, 94.1%, 100% and 62.5%, respectively. Compared with school types, detection rate of the ACM in Kindergarten, Elementary, Middle, High, Special Education schools were 100%, 97.1%, 92.9%, 100%, 80%, respectively. Ceiling textiles contained chrysolite/mixed amosite(2~8 %) and wall cement flat boards contained chrysolite(6~11 %). Also, gasket contained chrysolite(16~17 %), slate roof contained chrysolite(10~13 %). In this study, risk assessment EPA AHERA rule of ACM showed that all materials were "Pool" grade. And, ASTM rule risk assessment showed that all materials were "Q&M program" grade.

• Journal of Environmental Health Sciences
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• v.41 no.6
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• pp.369-379
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• 2015

Objectives: The lack of reliable information on environmental pollution and health impacts related to asbestos contamination from abandoned mines has drawn attention to the need for a community health study. This study was performed to evaluate asbestos-related health symptoms among residents near abandoned asbestos mines located in the Chungcheong Provinces. In addition, exposure assessment for asbestos is needed although the exposure to asbestos was in the past. Methods: Past exposure to asbestos among inhabitants near abandoned asbestos mines was estimated by using surface sampling of deposited dust in indoor and outdoor residences. A total of 54 participants were divided into two groups with (34 cases) and without (20 controls) diseases related to asbestos. Surface sampling of deposited dust was carried out in indoor and outdoor residences by collecting 105 samples. Deposited dust for sampling was analyzed by polarization microscope (PLM) and scanning electron microscope?energy dispersive x-ray spectrometer (SEM-EDX) to detect asbestos. Subsequently, the elements of the deposited dust with asbestos were analyzed by SEM-EDX to assess the contribution of sources such as abandoned mines, slate and soil. Results: Among the 105 samples, asbestos was detected by PLM in 29 (27.6%) sampling points, and detected by SEM in 56 (48.6%) sampling points. Asbestos in indoor residences was detected by PLM in four sampling points, and by SEM in 12 sampling points. Asbestos detection in indoor residences may be due to ventilation between indoors and outdoors, and indicates long-term exposure. The asbestos detection rate for outdoor residences in the case group was higher than that in the control group. This can be explained as the case group having had higher exposure to asbestos, and there has been continuous exposure to asbestos in the control group as well as the case group. Conclusion: Past residential asbestos exposure may be associated with asbestosis among local residents near abandoned asbestos mines. Odds ratios were calculated for asbestos detection in outdoor residence by logistic regression analysis. Odds ratio between asbestos detection and asbestosis pulmonum was 3.36 (95% CI 0.90-12.53) (p=0.072), adjusting for age, sex, smoking status and work history with multi-variable logistic regression by PLM analysis method.

• The Journal of Engineering Geology
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• v.8 no.2
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• pp.131-143
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• 1998

The study area, Beulgok-myon Nonsan-goon Chungcheongnan-do is consist of Changri slate(Och, okcheon system), lithic tuff(Kslt, kyoungsang system), granite (Kqb, kyoungsang system) and quartz porphyry(Kgf, kyoungsang system). More than 3000 joints were measured and classified by direction. Main dipdirection/dips of Kqb are 228~257/73~88, 010~150/70~85, Och are 134~164/40~90, 214~249/55~89, Kslt are 291~332/75~82, 235~241/73~71. But Kgf are not appeared distinct directions of joint. In field, p-wave velocities(Vp) are measured on the bed rock. Vp of Kgf are $5000m(240^{\circ})~2380(360^{\circ})m/s$, Kqb are $3846(210^{\circ})~1408(150^{\circ})m/s$, Kslt are $5000(360^{\circ})~2323(150^{\circ})m/s$ and Och are $6657(180^{\circ})~2000(030^{\circ})m/s$. Also P-wave velocities on specimen are measured. It is slightely higher than it's measured on the bed rock. For engineering properties of rock, we measured Poisson's ratio, rigidity, Young's modulus and bulk modulus by dynamic method.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.361-367
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• 2014

This paper investigates the punching shear strength of lightweight aggregate concrete (LWAC) slabs through a series of experimental study. Five full scale slabs were constructed using normal concrete and four different types of LWAC. Each lightweight aggregate (LWA) used in this study had different sources (clay, shale, or slate) and shapes (crushed or spherical shape). Based on the test results, the effect of the lightweight aggregates (LWA) on the punching shear behavior was investigated. From the test results, it was found that the punching shear failure surface of LWAC slab with spherical shape coarse aggregate was less inclined than that with crushed shape coarse aggregate, which resulted in an increase of the area of the shear failure surface. As a result, it leads to the increased punching shear strength of the slab. On the other hand, the failure surfaces of LWAC slab with crushed shape coarse aggregate and normal coarse aggregate were inclined similarly. Finally, the test results of this study were compared with the punching shear strength obtained from current design models, such as ACI and CEB-FIP, to examine the validation of current design model to predict the punching shear strength of the LWAC slab.

• Journal of Preventive Medicine and Public Health
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• v.18 no.1
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• pp.1-11
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• 1985

A decade ago a survey on the population-base incidence rate of anthracite coal gas (mainly carbon monoxide) poisonig in Seoul area was investigated, resulting in the incidence rate of 306/10,000 risk population and 1 death/10,000. Another survey on the carbon monoxide poisoning was investigated during 1 year period from Apr. 1983 to Mar. 1984. Total subjects of risk population were 67,740 households covering 353,287 persons. The major findings of this survey are as follows: 1. Household-base incidence rate was 8.4% spell-base 10.4%. 2. The incidence rate was the highest in houses having each of slate roof, cement wall, vinyl floor of bedroom and direct 'ondol' heating system. 3. Average 2.1 person was attacked from one incidence of the poisoning; severity-wise person-base incidence rates per 10,000 were 352 in mild poisoning, 54 in severe poisoning and 1.4 in death-overall incidence rate 407. Several facts were identified which supported that this figure was moderately underestimated. As the incidence of the poisoning is affected by socioeconomic and environmental factors, it is natural that one expects the incidence will decrease in proportion to genernal improvement of the above factors. Thus the results of these two surveys seemed preposterous. But further study suggested that the incidence rate (306/10,000) decade before had been significantly underestimated and corrected-rate should have been 478/10,000 level. 4. Age and sex distribution by the degree of the poisoning was uniform with little statistical difference; overall incidence rates by sex were 339/10,000 in male and 475/10,000 in female with significant statistical difference(p<.01). 5. 5.3% of the patients were treated at hospital or local clinic; 3.0% of the patients were hospitalized. Admission rate in comatose patient(severe poisoning) was 14.2%. In conclusion, carbon monoxide poisoning remains a major health problem by now.

• Journal of Animal Environmental Science
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• v.10 no.1
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• pp.37-46
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• 2004

In order to investigate the effect of floor condition on the fattening performance of cattle, sixteen finishing Hanwoo steers of weighting 570kg were fed for 16 weeks to slaughter on two types of sawdust bedding pen oriented to the south(SP) and the north(NP) then obtained following results. The floor condition of SP roofed by transparent material was dry and flat during overall experimental period, whereas, that of NP roofed by solid slate was muddy and rough even in summer and fall, and then frozen in winter period resulted in interfering with the locomotion and resting behavior of steers. Average daily dry matter intake of steers was not different between tow treatments, however, the average daily gain of steers in NP and SP was 0.64kg and 0.75kg, respectively, meaning that gained 14.3% less for the NP group(p<0.05), accordingly, feed requirement(feed/gain) and TDN/gain increased by 15.9% and 15.5%, respectively. No significant differences were found in slaughter weight, carcass weight, dressing percentage, meat yield index and meat quality traits between two treatments. In conclusion, this study revealed that poor floor condition of feeding pen could decrease weight gain and feed efficiency of cattle by increasing energy consumption for locomotion and conductive energy loss while resting on the floor surface. These results indicates that housing orientation of cattle shed and the selection of roof material are important factors in beef cattle production.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.689-696
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• 2008

The purpose of this study was to evaluate the alkali-silica reactivity for aggregates in Korea according to test methods: accelerated mortar bar test (AMBT) by ASTM C 1260; chemical test by KS F 2545 (ASTM C 289). The results are as follows: The AMBT (ASTM C 1260) results showed that two (2) igneous rocks (two mica granite and felsite), three (3) sedimentary rocks (arkose, red sandstone and shale), two (2) metamorphic rock (slate and vitric tuff), one (1) mineral (quartz) showed more expansion than 0.1% at 14 days. But, some sedimentary rocks and metamorphic rocks expanded more than 0.1% at 28 days even though they were less than 0.1% at 14 days. Therefore, it is necessary to extend the experimental dates more than 14 days to evaluate the possibility of alkali-aggregate reactivity. The chemical test (KS F 2545) results showed that five (5) igneous rocks (andesite, diabase, granite porphyry, muscovite granite and diorite) were indicative of potentially deleterious expansion, while two (2) igneous rocks (diorite porphyry and quartz porphyry) were possible indicative of expansion, and three (3) igneous rocks (biotite granite, two mica granite and felsite) were indicative of innocuous reactivity. The above results showed that the results from chemical method (KS F 2545) and AMBT (ASTM C 1260) had little relationship.