• Proceedings of the Korean Society of Disaster Information Conference
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• 2022.10a
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• pp.235-236
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• 2022

본 논문에서는 업무상 사고 재해자와 사망자가 가장 많은 공사금액 20억 원 미만 소규모 건설현장에서 떨어짐 재해를 줄이는 방안을 제시하여 전체 건설현장의 재해 감소에 기여하고자 하였다. 연구에 기반이 되는 이론(하인리히 법칙, 버드의 도미노 이론과 하베이 3E이론)을 검증하기 위하여 자료를 분석하고 국내·외 사례를 통해 선행연구를 실시하였다. 그 결과 떨어짐 재해발생원인을 다음과 같이 도출하였다. 첫째, 근로자의 안전·보건의식이 부족하다. 둘째, 떨어짐 방지 안전시설이 미비한 현장이대다수이다. 셋째, 위험성평가 제도의 현장 적용이 난이하다. 또한, 사례연구 분석을 통해 2015년~2016년 OO지역의 떨어짐 재해가 발생한 공사금액 20억원 미만 약 15개소 소규모 건설 현장을 방문하여 현장 소장을 대상으로 인터뷰를 실시하였다. 본 연구에서는 공사금액 20억 원 미만 소규모 건설현장의 떨어짐 재해를 줄이기 위한 개선방안으로 자발적으로 체험할 수 있는 근로자 교육, 떨어짐 방지 안전시설을 지원해주는 정부지원 그리고 위험성평가 간소화를 제안하였다.

• Journal of the Korean Institute of Telematics and Electronics
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• v.12 no.2
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• pp.18-23
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• 1975

The dc conductivity, ac conductivity and switching effect of As.Te-Si.Ge have beon investigated. The dc conductivity ranged from $3{\times}10^{-7}{\Omega}^{-1}cm^{-1}$ to $1.5{\times}10^{-8}{\Omega}^{-1}cm^{-1}$ at room temperature and was found to be expressed by ${\sigma}$ = ${\sigma}_0$exp(-${\Delta}$E/kT) below the phase transition temperature Tg. The ac conductivity was much higher than dc conductivity and this result is consistent to experimental formula ${\sigma}$(w)=${\sigma}_0+Aw^n$. In the temperature range of 298$^{\circ}K$ ~ $473^{\circ}K$ the ac conductivity was independent of temperature at 200KHs. At lower frequencies the ac conductivity increased strong1y with temperature. Also, it has been found that all samples showed a threshold switching, but not a memory switching.

• Composites Research
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• v.34 no.2
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• pp.88-95
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• 2021

VARTM (Vacuum-assisted resin transfer molding) process is a low-cost process technology and affiliated with OoA (Out of Autoclave). Besides, it has been widely used in various fields. However, because of its lower quality than the autoclave process, it isn't easy to apply the VARTM process to the aerospace industry, which requires high reliability. The main problem of the VARTM process is the loss of mechanical properties due to the low fiber volume fraction and high void content in comparison to the autoclave. Therefore, many researchers have studied to reduce void and increase fiber volume fraction. This study examines whether the method of controlling atmospheric pressure could increase the fiber volume fraction and reduce void during the resin impregnation process. Reliability evaluation was confirmed by compressive strength test, fiber volume fraction analysis, and optical microscopy. As a result, it was confirmed that increasing the atmospheric pressure step by step in the VARTM process of impregnating the preform with resin effectively increases the fiber volume fraction and reduces void.

• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.1
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• pp.13-26
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• 2023

Recently, as the development of underground spaces has become active due to rapid urbanization and population density, interest in the ground behavior according to the construction of underground spaces is increasing. In large cities with high population density and many buildings, ground subsidence has a great impact on structures and there may be a risk of collapse, so the analysis of ground behavior due to underground construction is essential. Previous studies have been conducted on the subsidence pattern of the surface and the deformation of the tunnel when constructing the tunnel, but analysis has rarely been conducted by using actual topographic information. Therefore, this study analyzed the difference in ground behavior between the actual topography and the flat topography. As a result, it was confirmed that ground settlement occurs at higher elevations, such as in mountainous topography, and when the numerical analysis is performed considering topographical information, the crown settlement of the tunnel is up to about approx. It showed a difference of 10 mm, and it was found that the sensitivity was less in the case of displacement of tunnel wall compared to the crown settlement and ground settlement. The numerical analysis considering the actual GIS-based topographic information presented in this study can be used to obtain more accurate surface subsidence data to understand the behavior of the upper structure due to tunnel excavation.

• Fire Science and Engineering
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• v.34 no.2
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• pp.86-93
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• 2020

This study aims to maintain the safety of an outdoor storage tank through the fundamental case analysis of explosion and fire accidents in the storage tank. We consider an accident caused by the explosion of fire inside the tank, as a result of the gradual spreading of the residual fire generated by wind lamps flying off a workplace in the storage tank yard. To determine the cause of the accident, atmospheric diffusion conditions were derived through CCTV image analysis, and the wind direction was analyzed using computational fluid dynamics. Additionally, the amount of oil vapor inside the tank when the floating roof was at the lowest position, and the behavior of the vapor inside the tank when the floating roof was at the highest position were investigated. If the cause of the explosion in the storage tank is identified and the level of the storage tank is maintained below the internal floating roof, dangerous liquid fills the storage tank, and the vapor in the space may stagnate on the internal floating roof. We intend to improve the operation procedure such that the level of the storage tank is not under the Pontoon support, as well as provide measures to prevent flames from entering the storage tank by installing a flame arrester in the open vent of the tank.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.3
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• pp.1209-1214
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• 2016

Background: Cigarette smoking constitutes a major threat to the health and wellbeing of teenagers. While smoking has been on decline in the developed countries, the reverse is the case in developing countries. The aim of this study was to determine the age of initiation, determinants and prevalence of cigarette smoking among teenagers in Mushin Local Government Area of Lagos state, Nigeria. Materials and Methods: This was a descriptive cross-sectional study among 475 teenagers selected by multistage sampling. A pre-tested, structured, interviewer-administered questionnaire was used for data collection. The study was carried out in November, 2014. Results: Response rate was 84.6%. Mean age of the respondents was $16.4{\pm}1.65years$. Range and mean age of initiation of cigarette smoking were 7 to 17 years and $12.0{\pm}3.32years$ respectively. Teenagers who were above 15 years (OR:5.13, 95%CI: 0.87-30.26), males (OR:5.19, 95%CI: 1.57-17.18), married (OR:8.41, 95%CI: 1.04-63.35), had ${\leq}$primary school education(OR:4.31, 95%CI: 1.07-17.33), influenced by friends(OR:308.84, 95%CI:84.87-1123.81), and influenced by advertisements (OR:27.83, 95%CI: 3.92-197.64) were more likely to have initiated cigarette smoking. Furthermore, teenagers who were males (OR:12.77, 95%CI: 2.90-56.28), married (OR:19.24, 95%CI: 2.05-180.45), had ${\leq}$primary school education(OR:7.85, 95%CI: 2.37-26.01), influenced by friends(OR:28.56, 95%CI: 10.86-75.07), and influenced by advertisements (OR:5.95, 95%CI: 1.72-20.61) were more likely to be current cigarette smokers. In addition, 24.9% had initiated cigarette smoking while 14.7% were current smokers of cigarette. Conclusions: Mean age of initiation of cigarette smoking was $12.0{\pm}3.32years$. Determinants of cigarette smoking were age, gender, marital status, educational background, friends and advertisements. Life time prevalence of cigarette smoking was higher than prevalence of current cigarette smokers. Cigarette smoking reduction programs should take these factors into consideration.

• Journal of the military operations research society of Korea
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• v.34 no.2
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• pp.163-174
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• 2008

The military is an organization where reliability and availability take much more importance than in any other organization. And, in line with a recent trend of putting emphasis on 'system readiness', not only functions but also availability of a weapon system has become one of achievement targets. In this regard, the military keeps spares for important facility and equipment, which is called as Maintenance Float (M/F), in order to enhance reliability and availability in case of an unforeseen event. The military has calculated yearly M/F requirements based on the number of equipment and utilization rate. However, this method of calculation has failed to meet the intended targets of reliability and availability due to lack of consideration on the characteristics of equipment malfunctions and maintenance unit's capability. In this research, we present an analysis model that can be used to determine an optimal M/F inventory level based on queuing and absorbed Markov chain theories. And, we applied the new analysis model to come out with an optimal volume of K-1 tank M/F for the OO division, which serves as counterattack military unit. In our view, this research is valuable because, while using more tractable methodology compared to previous research, we present a new analysis model that can describe decision making process on M/F level more satisfactorily.

• Korean Journal of Environment and Ecology
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• v.30 no.5
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• pp.908-914
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• 2016

Both interests in nature-friendly education and demands for nature experience program are steadily increasing in children education field in korea. This study aims to find out that five-sense experience-activity with healing factors of forest can have an effect on both self-efficacy and respectful recognition of life of children. 5-year-old young children were chosen as the subjects for this study. Test group participated two times a week in the special forest class in a children education institute in Chungju oo-dong while control group did not. Both test group and control group were composed of 20 young children respectively and each group were 11 boys and 9 girls respectively. The five senses experience activity program was conducted two sessions a week from 8 August to 20 September in 2016 and each session was one hour (60 minutes) long. Five senses experience activity is an activity that young children awaken their five senses in the forest, recognize seasonal change with their five senses, build up their selves and become intimate with nature. Before and after the program self- efficacy test and respectful recognition of life test were conducted and the data was analyzed using SPSS 18.0 program. The results indicated that after participating five senses experience activity program both children's self-efficacy which means having positive-thinking and self-confidence and respectful recognition of life which means valuing nature coexisting with nature were improved significantly(p<0.05). Through five senses experience activity young children felt nature freely and to their heart's content with their bodies and five senses experience activity had better positive impacts on children's self- efficacy and respectful recognition of life than classroom activities.

• Journal of the Korean Geotechnical Society
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• v.21 no.8
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• pp.63-72
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• 2005

Rocks are dumped to soft marine ground in order to improve trafficability and construction conditions in the tideland reclamation construction sites. Though this rock layer under earth fill has caused in a serious seepage problems after construction, seepage behaviors of this embankment structure is not correctly investigated. Water flow through rock layers is, in general, known as Non-Darcy's flow. However, the embedded rock layer under earth fill is not known whether its flow is governed by Darcy's or Non-Darcy's law. Therefore, a numerical analysis, laboratory model test and filed investigations were performed for analyzing the those seepage characteristics in this research. Results show that there is significance of $95\%$ of confidence between observed heads and seepage rates, and the calculated ones by SAMTLE which is developed under the assumption that the water flows through the two-layer system obey the Darcy's flow. And after operating the hydraulic gradient(i) of $0.10\~0.55$ upon laboratory model, these seepage characteristics of the embedded rock layer show that Reynolds Numbers are less than 10 and the relationship between these velocities of rock layer(v) and hydraulic gradients(i) is linearly proportional with more than 0.79 of the coefficient of correlation $(R^2)$. And the Reynolds Number of the velocity calculated by the relation of v=ki in the embedded rock layer of OO sea dike is $1\~6$. It shows also laminar flow. Based on these results, it is concluded that the seepage characteristics of embedded rock layer under earth fill can be laminar and Darcy's flow.

• Journal of the Korean Institute of Gas
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• v.26 no.6
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• pp.45-51
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• 2022

Technologies for collecting and treating pollutants from point sources are steadily being developed, but Non-point sources, it is difficult to develop emission treatment technologies and effective emission coefficients. However, since non-point sources make up about 60% of domestic emissions, and first of all, the method of calculating emissions should be reasonable, and the workplace should develop emission reduction technologies based on this. This study suggest the effectiveness and improvement of the emission coefficient currently used for the petrochemical industry with high emissions. The emission characteristics of non-point sources emission were confirmed by analyzing the LDAR (Leak Detection And Repair) data of OO company located in Yeosu, Jeollanam-do over the past five years. As a result, there was no difference in discharge characteristics according to fluid phase, but it was confirmed that there was a difference in the size of the device and the characteristics of each manufacturer. In addition, it was confirmed that the emission coefficient applied in the petrochemical industry was larger than that of the refining industry, and improvement measures were suggested. Through these studies, it is expected that emission coefficients specialized in the petrochemical industry can be applied and that the workplace itself will contribute to the development of technologies that can drastically reduce them.