• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.870-877
• /
• 2020

A suction bucket foundation, especially useful at depths of more than 20m, is a method of construction. The method first places an empty upturned bucket at the target site. Then, the bucket is installed by sucking water or air into it to create negative pressure. For stability, it is crucial to secure the verticality of the bucket. However, inclination by the bucket may occur due to sea-bottom conditions. In general, a repeated intrusion-pulling method is used for securing verticality. However, it takes a long time to complete the job. In this paper, we propose a real-time suction bucket verticality monitoring system. Specifically, the system consists of a sensor unit that collects raw verticality data, a controller that processes the data and wirelessly transmits the information, and a display unit that shows verticality information of a circular steel pipe. The system is implemented using an inclination sensor and an embedded controller. Experimental results show that the proposed system can efficiently measure roll/pitch information with a 0.028% margin of error. Furthermore, we show that the system properly operates in a suction bucket-based model experiment.

• Proceedings of the KAIS Fall Conference
• /
• 2011.12b
• /
• pp.417-420
• /
• 2011

본 논문에서는 자전거의 구동 및 변속 창치인 스프라켓에 관한 연구이다. FEM을 이용하여 티타늄 소재 스프라켓의 구조해석을 수행하기 위해 10단 Cassette를 설계하였고, 사용자가 가장 많이 사용하는 단수인 4, 5, 6단을 티타늄 소재로 선정하였다. 티타늄 재료의 물성치를 실험을 통해 확보하였으며, 이를 이용하여 티타늄 스프라켓의 각 치형에 걸리는 Equivalent Stress를 구하였고 스프라켓 고정장치인 스파이더와의 체결 후의 Equivalent Stress를 구하여 티타늄 스프라켓의 안정성을 확보한다.

• Proceedings of the KAIS Fall Conference
• /
• 2011.05a
• /
• pp.332-335
• /
• 2011

원적외선, 음이온 방출과 항균, 탈취, 난연등의 효과를 가지는 황토를 합성수지와 혼합하여 복합소재를 연구하여 환경 친화적인 특징과 원적외선, 음이온의 방출을 이룰 수 있는 복합소재 조성을 연구하였다. PP는 MI가 2~60이고, TPE로 Ethylene계을 사용하였으며, 황토와 PP의 혼련을 도와주기 위하여 MA-g-PP를 첨가하였고, 활제, 분산제 및 산화방지제를 첨가하여 compounding 하였다. 또한 황토의 종류에따라 적황토, 호황토, 홍토, 백토, 흑토등으로 구분되고, 각각의 황토 마다 다양한 종류의 입도를 가지고 있으며, 또한 환경 친화적이며 난연성을 부여하기 위하여 다양한 조성으로 compounding 하였다, 황토의 종류에 따른 복합재료의 물성으로부터 기계적 특성치, 원적외선 방사율, 난연성등을 확인하고, 친환경 난연 복합소재 기술을 연구하였다. 적황토의 경우 황토의 함량이 많을수록 인장강도는 작아지는 경향을 나타냈으며, 입도가 작을수록 인장강도가 커지는 경향을 나타냈다. 파단신율의 경우 적황토(#2000)에서 가장 양호하게 나타났으며, 굴곡강도, 충격강도의 경우 적황토(#5000)에서 MI 의 경우 적황토(#325)에서 양호하게 나타났다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.7
• /
• pp.78-84
• /
• 2019

The purpose of this study is to investigate the relationship between risk perception, knowledge, risk attitude, and health promoting behaviors of nursing college students. The data were collected from 168 university students of four-year nursing college in the city of D, C. The collected data were analyzed by independent t-test, one way ANOVA and Pearson correlation coefficient using SPSS WIN 20.0 program. As a result this study knowledge of fine dust was statistically significant in respiratory disease(t=1.92, p<.001). The risk attitude toward fine dust was statistically significant in respiratory diseases(t=2.05 p=.042), subjective health status(F=3.79, p = .012). There was a significant positive correlation between risk perception of fine dust and knowledge(r=.340, p<.001), risk attitude(r=.492, p<.001), and health promoting behaviors(r=.354, p<.001). Knowledge of fine dust and risk attitude(r=.401, p<.001), health promoting behavior(r=.296, p<.001), risk attitude toward fine dust and health care behaviors(r=.550, p<.001) also showed a statistically significant positive correlation. Based on these results, it will be necessary to develop a program to improve awareness and knowledge of fine dusts in nursing college students and to improve health promoting behaviors.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.1030-1033
• /
• 2009

고형연료(RDF)는 가연성 폐기물을 성형된 형태로 만드는 것으로 화석연료의 대체 에너지로 이용되어질 수 있을 뿐만 아니라 일반 소각설비에 비해 수송성, 저장성이 뛰어나며 발열량이 거의 일정하여 연소 안정성이 우수하고 액체연료나 기체연료의 비해 경제성과 안정성이 높다는 장점이 있다. 하지만 고형연료의 미량 포함되어 있는 중금속 물질에 의해 연소장치의 부식이나 시설 노후 촉진화와 같은 원인을 제공하며, 심각한 환경오염원의 전구물질이 생성될 수 있어 실용화에는 큰 장해 요인이 되고 있다. 따라서 본 연구에는 고형연료의 재료가 되는 폐기물을 분석하여, 중금속성분이 미치는 영향을 조사하고 부존자원의 최적 이용 방안을 도출하며, 이를 바탕으로 부존자원 액상/고상 연료화 기술, 부존자원 복합이용시스템, 폐열활용 시스템과 같은 기술에 적용하여 부존자원 재활용 및 에너지를 최적 활용할 수 있는 D/B 구축을 하는 것이 최종 목표이다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.13 no.7
• /
• pp.3275-3284
• /
• 2012

This study analyzed a 3D hydrodynamic advection diffusion using the EFDC model (Environmental Fluid Dynamics Code) in the agriculture lake to prevent stratification when we install a water circulator. EFDC model was predicted the range of the water circulator and various operational parameters ware derived for minimize the impact of the internal lake. Through EFDC simulation, water circulation is started overall circulation after 30days and a lake overall circulation showed that it was possible operated the water circulator after about 100days. Also, advection diffusion concentration was low in a lake when water circulator operate intermittent condition than continuous condition. And the entire circulation was stable in this condition. The S/B (Surface/Bottom) ratio can reduce the impact of lake as the surface water mixing a lot of. When the same condition (S/B ratio(3:1)), Case 8 (50days operation: 50days stop) of condition were able to minimize the impact of lake.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.176-183
• /
• 2018

Climate change, rapid urbanization, and population concentration have led to a higher frequency and magnitude of disasters in the world. Recently, the occurrence of large-scale complex disasters, which are caused by a combination of natural disasters, man-made disasters, and social disasters, is increasing. In Korea, there are many case studies of damage prediction and response technology development for individual natural disasters, such as earthquakes, floods, and typhoons. On the other hand, the system basis for the efficient response and management of large-scale complex disasters is insufficient. Therefore, this study examined the representative cases of natural, social disasters, and related cases of domestic disaster response management systems. In addition, this paper proposes ways to improve the legal system for complex disaster management policies and establish a cooperation system between the ministries for an efficient response.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.11
• /
• pp.4656-4663
• /
• 2010

In this study, the 3D computational fluid dynamics (CFD) was performed in relation to the internal fluid characteristics, flow distribution, air mean ages, and residence time for the development of the most optimal model in the complex post-disposal device. As it is expected that a channeling (drift) would be made by the semi-dry reactor due to the large difference in the flow distribution by the compartment in the bag filter, a structural improvement should be urgently made for more uniformed flow distribution in the bag filter. In addition, it showed the possibility that the velocity field and distribution characteristics of the residence time could be improved through a modification to inlet structure of the spray dryer reactor. The complex post-disposal device, modified and supplemented with this analysis, integrated the semi-dry reactor and the bag filter in a single body, so it follows that the improvement can make the device compact, the installation area, the operation fee, and management more convenient.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.6
• /
• pp.27-36
• /
• 2018

A significant amount of studies were performed on evaporation heat transfer and pressure drop in microfin tubes. Most studies, however, focused on the refrigerants used in air-conditioners or heat pumps, and very limited information is available on R-404A, which is used in low temperature refrigeration. In this study, the evaporation heat transfer and pressure drop characteristics of R-404A in a 9.5 mm O.D. microfin tube were investigated for the mass flux range from $80kg/m^2s$ and $200kg/m^2s$. A smooth tube of the same outer dimeter was also tested for comparison. The results showed that the heat transfer enhancement ratio of the microfin tube increased with increasing mass flux and the heat flux decreased. The relative contribution of the convective heat transfer and the heat flux on total heat transfer was attributed to the observed trend. The pressure drops of the microfin tube were slightly (maximum 28%) larger than those of the smooth tube. Existing correlations do not adequately predict the measured heat transfer coefficients of pressure drops, probably due to the test range of the present study, which is outside of the existing correlations.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.2
• /
• pp.496-506
• /
• 2021

This study examined the relationship between job stress and fatigue symptom of fire-fighting officials. The study subjects were 330 fire-fighting officials working at five fire stations in the D metropolitan city. The study survey was a structured self-administered questionnaire from September 1 to October 31, 2019. The level of fatigue symptoms and job stress were significantly higher (p<.0.001). By the sub-region, the level of fatigue symptoms and job demand were significantly higher (p=0.046), but the decision latitude, the supervisor support, and co-worker support were lower (p=0.006, p<0.001, and p<0.001, respectively). The level of fatigue symptom showed a significant positive correlation with the total score of job stress (r=0.348, p<0.05) and the job demand (r=0.301, p<0.05). In contrast, it showed a significant negative correlation with the decision latitude (r=-0.306, p<0.05), supervisor support (r=-0.340, p<0.05), and co-worker support (r=-0.355, p<0.05). Multivariate logistic regression showed that the odds ratio of the high-risk fatigue group was significantly higher in the high-risk group of job stress than in the low group of job stress (ORs=3.03, 95% CI=1.13~8.12). These findings suggest that the level of fatigue symptoms of fire-fighting officials is related significantly to job stress.