• Journal of Preventive Medicine and Public Health
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• v.24 no.3 s.35
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• pp.279-286
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• 1991

Much of the working population in developing countries are engaged in shift work now and the number of shift workers is not expected to decrease in the future mostly because the need for continuity of production is increasing. Therefore, the possible effects of shift work on health are of particular interest, and in fact, there have been many epidemiological studies on shift work since the first world war. However, no studies on health effects of shift work have been reported in Korea, and the existing studies in western world have arrived at quite different conclusions mainly because the conditions of work other than shift work, such as age and selection of workers, work environment, and labor conditions also influence the health of workers. This study was firstly carried out in Korea to investigate the health risks related to shift work with 2,093 female workers randomly selected from three major manufacturing industries in proportion to total number of female workers in those industries. Differences of work conditions other than shift work in this study were adjusted by multivariate analysis. Ma findings obtained from this study are as follows : 1. There were significant differences between shift and day workers in the distribution of age, type of industry, condition of noise and dust, regularity of mealtime, working position, and working duration. Shift workers tended to be younger, to have shorter working duration, to have more irregular mealtime, to work in standing position, and to work under more noisy and dusty environment than day workers. 2. Univariate analysis showed that shift work increased the Todai Health Index (THI) scores of digestive tract, respiratory tract, and mental instability symptom categories. Shift work also increased days of sickness absence and number of industrial accident per 100 workers per month. 3. Multivariate analysis that adjusted the differences of demographic, occupational and non-occupational health-related working conditions showed that digestive tract symptom and mental instability symptom scores were significantly higher in shift workers than those in day workers. Based on these study results, it is concluded that the shift work has significant effects on some psychophysiological conditions of the workers and the effects are also influenced by several other personal and working conditions.

• Korean Journal of Ecology and Environment
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• v.47 no.2
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• pp.82-90
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• 2014

To assess the adverse effects of suspended solids on fishes, the hatching rate of embryo, and survival and growth of larvae were measured with common fish species of river such as crusian carp (Carassius auratus), common carp (Cyprinus carpio) and medaka (Oryzias latipes). Bioassay on hatching rate of embryo was conducted with a range of turbidity as 10 levels from 0.2 to 8,080 NTU. Another bioassay on 4-day larval survival and 21-day larval growth were also conducted with a range of turbidity as 8 levels from 0.1 to 8,260 NTU, and 6 levels from 0.7 to 2,030 NTU, respectively. The hatching rate of C. auratus was not significantly different from that of control at turbidity below 4,040 NTU, whereas it decreased when turbidity was 8,080 NTU (p<0.05). The hatching rate of C. carpio was not affected by concentration of suspended solids. For O. latipes, the hatching rate significantly decreased from 254 NTU (p<0.001) and it was zero when turbidity was 8,080 NTU. The 4-day survival of larvae of all 3 species was not affected by turbidity, while the larval growth of all 3 species was significantly affected. The turbidity effect on the growth of C. auratus and C. carpio was observed from 7 days after the exposure at turbidity level of 145, 143 NTU, respectively. The turbidity effect on the growth of O. latipes was observed from 14 days after the exposure at turbidity level of 254 NTU. The results of this study will provide the basic information for the derivation of water quality criteria on suspended solids for the protection of aquatic ecosystem and the quantitative ecological risk assessment of freshwater environment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.5
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• pp.389-401
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• 2016

This study attempted to present the monthly distribution of the inshore gill netters for the prevention of propeller failure caused by the damage of fishing gear by the merchant vessels in the West Sea. This study was conducted using the transmitting device of fishing location (V-Pass) data for 1 year in 2014. The grid intervals are $30minute{\times}30minute$ ($latitude{\times}longitude$) based on the section of the sea. A total of 56 sections were analyzed by constructing a grid. The results revealed that the section no. 194 with the highest density index showed no fishing gear damage accident. But the section no. 193 with a relatively lower density index showed more frequent fishing gear damage accident. It is because the section no. 193 is included in the main route of the merchant vessels. Based on this analysis, it is found that the fishing gears are not damaged in proportion to density index but risk of damage exists according to the main routes of merchant vessels. Therefore, for the safe navigation of the merchant vessels, notifying the waters of $34.5^{\circ}{\sim}35.5^{\circ}$ at latitude and $125.67^{\circ}{\sim}126^{\circ}$ at longitude, as a navigational warning area from May through September, will prevent marine accident, such as propeller failure and fishing gear damage. Accordingly, when the merchant vessels navigate in the section no. 193 and 203, the area of $34.5^{\circ}{\sim}35.5^{\circ}$ at latitude and $125.5^{\circ}{\sim}125.67^{\circ}$ at longitude is recommended for the safe navigation.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.6
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• pp.637-645
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• 2018

This study analyzes the problem of lack of anchorage caused by some anchorage closed and suggests ways to improve Masan anchorage. For this, we established the evaluation criteria, and analysed the anchorage operating rate during 5 years after estimating the capacity of barge, and suggested improvement plan after appropriateness assessment of anchorage capacity, finally verified the anchorage improvement plan. As a result of study, it is analyzed that the Masan A-2, A-4, A-6 anchorage needs to expand the anchorage due to excess the anchorage assessment criteria of 60 %. So, in order to improve the Masan anchorage, we suggested the improvement plan that extended 1.8 times by the group designated anchorage, according to integrating the A-2, A-4, A-6 anchorage and anchorage dwell time and ship type. And, the result of verification improvement plan, it is analyzed that meet the assessment criteria since decreasing the anchorage operating rate by 1/2 compared to the existing one, does not act as a risk factor in terms of maritime traffic.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.15
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• pp.6481-6490
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• 2015

Background: Esophageal cancer (EC) is among the most common malignancies in Eastern Africa, but the occurrence of EC in Sudan has rarely been described in the scientific literature. This paper reports the results of a consecutive case series of all EC patients who visited one of the two public cancer treatment centers in the country in 1999-2012, providing a first description of this disease in a treatment center located in central Sudan. Materials and Methods: Clinical and demographic data for all EC patients who visited the Department of Oncology of the National Cancer Institute at the University of Gezira (NCI-UG) from 1999 to the end of 2012 were abstracted and tabulated by sex, tumor type and other characteristics. Results: A total of 448 EC patients visited NCI-UG in 1999-2012, and the annual number of EC cases increased steadily from 1999. Squamous cell carcinoma (SCC) was the predominant EC tumor type (90%), and adenocarcinoma (ADC) was reported in 9.4% of the EC cases. The overall male-to-female ratio for EC was 1:1.8, but the ratio was tumor type-dependent, being 1:2 for SCC and 2:1 for ADC. Only 20% of EC patients reported having ever used tobacco and/or alcohol, and the vast majority of these patients were male. At the time of EC diagnosis, 47.3% of the patients resided in Gezira State. Some EC patients from Gezira State seek out-of-state treatment in the national capital of Khartoum instead of visiting NCI-UG. Conclusions: The annual number of EC patients visiting NCI-UG has increased in recent years, approximately half of these patients being from Gezira State. Although this consecutive series of EC patients who visited NCI-UG was complete, it did not capture all EC patients from the state. A populationbased cancer registry would provide more complete data required to better understand EC patterns and risk factors.

• Journal of the Korean Chemical Society
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• v.61 no.2
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• pp.51-56
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• 2017

N-nitrosamines are the nitroso compounds which are produced by nitrosation reactions of the secondary amine and nitrite under acidic conditions. Approximately 300 species of N-nitrosamine have been tested for carcinogenicity in laboratory experiments, with 90% of them demonstrated carcinogenic effects different animal species, including higher primates. In 1978, IARC classified NDMA and NDEA as Group 2A, and NDPA, NDBA, NPIP, NPYR and NMOR as Group 2B. In this study, we established pretreatment and analytical method for N-nitrosamines (NDMA, NDEA, NMEA, NDPA, NDBA, NPIP, NPYR and NMOR) in human urine for biological monitoring of N-nitrosamines. The analytes were extracted using solid phase extraction (SPE), then quantitative analysis was performed by LC-(APCI)-MS/MS. The accuracies of the established method were between 85.8~108.7% and precisions were lower than 20%. The limit of detection (LOD) were between 0.0002 (NDBA) and 0.0793 (NDMA) ng/ml. The linearity obtained was satisfying for the 8 N-nitrosamines, with a coefficient of determination ($r^2$) higher than 0.999. The mean concentrations of N-nitrosamines in the urine were 2.645 mg/g creatinine for NDMA, 0.067 mg/g creatinine for NDEA, 0.009 mg/g creatinine for NMEA, 0.011 mg/g creatinine for NDBA, 0.271 mg/g creatinine for NPIP and 0.413 mg/g creatinine for NPYR. NDPA and NMOR were not detected. It can be used as a instrumental methodology for evaluation and risk assessment of human exposure to N-nitrosamines for the further research.

• Korean Journal of Social Welfare
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• v.37
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• pp.357-379
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• 1999

In recent years, the subject of peer rejection in school settings has received increased attention in the massmedia and counseling literature. This study focused on the effect of individual and environmental factors on peer rejection. Dependent variable was the number of perpetrating peer rejection and independent variables were psychological, behavioral, familial factors, exposure of peer rejection and perception about school policies. Ordered Probit model was employed because of the nature of limited dependent variable. The data were collected from 714 middle-school student in Seoul. Major findings were as follows. First of all, the adolescents who has aggression and problematic behaviors in school were more likely to participate in peer rejection. Second, negative parent-children relationships and the family structure didn't have significant effects on peer rejection. And there were not a significant effect of attitude toward academic value and academic achievement on peer rejection. Third, environmental risk factors such as negative peer relationship and the exposure to rejection had a significant increasing effect on peer rejection. But consistent school policies didn't have a significant effect. In conclusion, this study confirmed that peer rejection in school settings was affected by school environment such as negative-peer relationship, and exposure to rejection. Therefore, comprehesive and systematic intervention programs should be required to ensure that all the pupils at school have a right to learn in a safe and fear-free environment.

• Journal of the Korea Concrete Institute
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• v.20 no.6
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• pp.713-719
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• 2008

Various types of coatings have been developed for use as reinforcement in concrete and to resist chloride environment. The most commonly used coatings are inhibited and sealed cement slurry coating, cement polymer compositing coating and epoxy coating. Cement slurry offers passive protection, epoxy coating offers barrier protection whereas polymer coating offers both passive protection and barrier protection. Moreover, damage during handling of the steel may result in disbondment of the epoxy coating, which would increase the risk of localized corrosion. In the present study, inhibiting technique was used to increase the calcium hydroxide content at the interface up to 20%. Calcium hydroxide provides a high buffering capacity that resists a local fall in pH and thus maintains the alkaline environment necessary to prevent chloride corrosion. This study examines the use of a calcium hydroxide coating on the steel surface to enhance the pH buffering capacity of steel-concrete interface. Finally, the chloride threshold level (CTL) of polymer inhibitive coating calcium hydroxide is evaluated.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.13 no.5
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• pp.131-154
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• 2018

While strong investments on startup and venture ecosystem prosper worldwide, growing interest on nurturing startup ecosystem in Korea is also on its way. However, korean entrepreneurial ecosystem currently results few successful business models with those continuous development of itself compared to the one in China, which is breeding more than 50% of unicorns internationally. Accordingly, this study examined how people in the venture ecosystem, especially in IT industry feel about themselves and startup itself and compared startup ecosystem in Seoul, Korea to the one in Chengdu, China considering each of economic, social and administrational environment. The study tried to provide an implication about the future orientation of Korea's starup and venture ecosystem to policy makers and the ones inside the environment to make a better one. Therefore, the study choose Seoul, Korea and Chengdu, China as geological specimens of startup ecosystem and conduct qualitative study by interviewing selected ones who work in startup incubator, accelerator specified to IT industry and started their own business in IT industry funded by startup reward program. The study categorize the result in social, economic, and administrative parts and screens whether the interviewees from both Korea and China have similar opinions toward each of questions and can be translated to have tendency or not in each part of study. According to the study, the national recognition of startup should be moved from means of maintenance such as restaurants, franchise business to IT startup especially based on software business for the sustainable flourish in Korean venture ecosystem. Investors including accelerator, Angel investors and VCs should be less risk-aversion and therefore prefer stake purchase to solely giving subsidies. The role of governors should be limited to be a middleman of the network, connecting each people in need inside the ecosystem and their reward program should focus on nurturing the growing ones, not just multiplying the numbers of startups to expand the size of entrepreneurial ecosystem. Since this study indicated that entire revision of startup ecosystem should be applied to make a better one, it could be used to design future entrepreneurial infrastructure and the ways of activating startup ecosystem elsewhere in Korea.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.6
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• pp.3081-3088
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• 2013

Phenolic contents and antioxidant activities were determined in the water and ethanol extracts from six species of edible seaweeds, Phaeophyceae (Laminaria japonica, Hizikia fusiformis and Undaria pinnatifida), Rhodophyceae (Porphyra tenera and Gracilaria verrucosa) and Chlorophyceae (Ulva lactuca). The highest extraction yield was observed in water extract (pH 8.0) of G. verrucosa (44.23 %) and phenolic content was the highest in ethanolic (75 %) extract of H. fusiformis (52.82 ${\mu}g/mg$). 25 % ethanolic extract from U. lactuca was found to have the highest DPPH radicals scavenging activity(19.29 %) and superoxide anion scavenging activitiy was higher in water extract (pH 8.0) from H. fusiformis (81.20 %) than that other seaweeds. Phenolic contents were strongly correlated with antioxidant activity in the six edible seaweeds extracts ($R^2$=0.852). Taken together, these results indicate that H fusiformis may be a excellent source for development of natural antioxidants.