• Fire Science and Engineering
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• v.29 no.4
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• pp.81-88
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• 2015

A low-cost device using the light-extinction method was developed to measure the optical smoke density in various fire experiments in the present study. The relative measurement accuracy of low-cost device was evaluated through the comparison of optical density measured by a high-cost standard device consisting of He-Ne laser, photo detector and various optical components. The low-cost device was composed of laser module, photocell and acrylic board. From the experiments using a smoke generator can be easily adjusted the smoke concentration, it was found that the low-cost device could measure the smoke density within the range of ${\pm}10%$, compared to the standard device. In addition, the reliability of low-cost device was also confirmed in the experiment using a polyethylene flame. Finally, it is expected that the low-cost device developed with real-time measurement and simple installation for measuring the smoke density will be used instead of the high-cost standard device.

• Tunnel and Underground Space
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• v.16 no.1 s.60
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• pp.85-94
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• 2006

In this study, scaled model tests were carried out to decide the optimal critical velocity, to prevent back layering in the case of fire in a long traffic tunnel. Realistic estimates were made for the time required for people to escape ken the tunnel and far the time required by the ventilation operator to increase the system speed to full capacity. The analysis, predicts that the emergency ventilation will start about 240 seconds after the tunnel fire. It was also found that prevention of back layering would occur within 4 minutes after fan operation. To find out optimal critical velocity, a 1/50 scaled model tunnel(diameter : 0.2 m and length : 20 m) based on the Froude similarity technique was constructed. Changing $\beta$ values in the Tetzner's equation, smoke propagation was observed. From the experiment, it was concluded that using a $\beta$ value of 0.5 to prevent back layering successfully allowed time for safe evacuation.

• Korean Journal of Remote Sensing
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• v.36 no.5_4
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• pp.1255-1266
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• 2020

In this study, a complex simulation prototype was developed for rapid and accurate prediction of chemical dispersion range in order to reduce human casualties caused by chemical accidents. Complex simulation considered the leakage momentum during the near-field dispersion to take into account the leakage characteristics of the chemical. In the far-distance dispersion process, the wind distribution of the existing model, which was presented uniformly, was improved using weather and topographical information around the accident site, to realize a wind field similar to the actual one. Finally, the damage range was more precise than the existing model in line with the improved near- and far-distance dispersion process. Based on the results of damage range prediction of the complex simulation, it is expected that it will be highly utilized as a system to support policy decision-making such as evacuation and return of residents after a chemical accident.

• Journal of Preventive Medicine and Public Health
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• v.41 no.5
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• pp.331-338
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• 2008

Objectives : The purpose of this study was to measure the workload of home visit care activities and their relative values. This study examined also factors that affect the workload of home visit care activities. Methods : The participants of this study were 126 home-helpers of 50 home visit care agencies at the 2nd Long-term Care Insurance Demonstration Project. The workload of home visit care activities was divided into total work and four dimensions ; physical efforts, mental efforts, stress and time. Home visit care activities consisted of four categories with 24 items. We used magnitude estimation method to measure their relative values of the four dimensions. The participants answered the relative values of each activities based on the reference service. We used the activity for supporting their elderly's evacuation as the reference service. Results : Most of the respondents were over 40 years old female. They consumed most their time supporting elderly's going out. They consumed their highest physical, mental efforts, and stress for activities of coping with emergency situation. The Pearson correlation coefficients showed significant relationships between workload and each dimensions. This study showed that all four dimensions are statistically significant predictors of workload of home visit care activities. Also, we found that the home-helper's career affects the workload of home visit care activities. Conclusions : The workload of home visit care activities could be explained by physical efforts, mental efforts, stress and time.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.84-93
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• 2020

In recent years, the scale of damage from disasters such as earthquakes and large-scale fires and floods that are occurring in Korea is increasing. Accordingly, interest in urban disaster prevention that combines living infrastructure such as roads and parks is boosting, and it is urgent to prepare measures to reduce the damage scale of local cities. The purpose of this study is to derive implications for disaster prevention measures in areas where disaster prevention safety of local cities is weak through examples of disaster prevention safety of local cities in case of disaster. To this end, this study analyzed the regional characteristics, current status, and disaster prevention problems of regional cities in Japan, and selected disaster-vulnerable areas, and considered the distance relationship between disaster prevention bases through road network analysis. In addition, road closure simulation using ArcGIS Network Analyst was conducted to analyze disaster prevention safety in the area. As a result, the situation of the village which has a high possibility of isolation by natural disasters was grasped in advance. Through this, the suburbs confirmed the necessity of supplementing the disaster prevention function through transportation maintenance such as forest roads, and it was found that the city needs to prepare a risk management system. Furthermore, this study suggests the need for research on areas with a high possibility of isolation, especially in areas where disaster prevention functions are weak in local cities in case of disaster, and shows countermeasures for disaster prevention measures and resident education.

• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.4
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• pp.97-105
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• 2007

This study has been focus to certify the run-up heights, losses of human lives and property damages due to the 1983 Central East Sea tsunami. We have conducted the interview with indigenous inhabitant and field surveying at the Imwon port, East sea in Korea in order to inquire into the state of things occurred during that period. It is also investigated how much well they are aware of the emergency action plan including the evacuation system. Base on the reliable interviews, we selected and surveyed 10 places at the Imwon port, where the historical maximum overflowing occurred due to the 1983 Central East Sea tsunami. The measured run-up heights are approximately $3.3m{\sim}4.0m$ at the selected 10 places and it is found that the sea water ran over the banks in Imwon stream about 700m upstream from the Imwon port. From this study we can suggest supplementing the present emergency action plan and supply the state-of-the-art inundation map.

• Journal of Korean Neurosurgical Society
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• v.60 no.6
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• pp.701-709
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• 2017

Objective : Chronic subdural hematoma is a common and relatively benign disease. However, recurrence is common after surgical treatment, and the recurrence rate varies from 5% to 33%. The aim of this study was to investigate the predictive factors for recurrence of chronic subdural hematoma. Methods : We analyzed data from 248 patients with chronic subdural hematoma who were treated by burr-hole craniostomy with a closed drainage system for hematoma evacuation in this five-year retrospective study. Results : Thirty-one (12.6%) patients underwent re-operation for recurrence of chronic subdural hematoma. Univariate analysis revealed that anticoagulation (p=0.0279), headache (p=0.0323), and preoperative midline shifting (p=0.0321) showed significant differences with respect to recurrent chronic subdural hematoma. We performed a multivariate logistic regression analysis and found that diabetes mellitus (odds ratio [OR], 2.618; 95% confidence interval [CI], 1.0899-6.2898; p=0.0314), anticoagulation (OR, 6.739; 95% CI, 1.1287-40.2369; p=0.0364), headache (OR, 2.951; 95% CI, 1.1464-7.5964; p=0.0249), and preoperative midline shifting (OR, 1.0838; 95% CI, 1.0040-1.1699; p=0.0391) were independent predictive factors for recurrence of chronic subdural hematoma. Conclusion : We showed that diabetes mellitus, anticoagulation, headache, and preoperative midline shifting were independent predictors of recurrence of chronic subdural hematoma.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.405-422
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• 2013

Atomic layer deposition(ALD) is a promising deposition method and has been studied and used in many different areas, such as displays, semiconductors, batteries, and solar cells. This method, which is based on a self-limiting growth mechanism, facilitates precise control of film thickness at an atomic level and enables deposition on large and three dimensionally complex surfaces. For instance, ALD technology is very useful for 3D and high aspect ratio structures such as dynamic random access memory(DRAM) and other non-volatile memories(NVMs). In addition, a variety of materials can be deposited using ALD, oxides, nitrides, sulfides, metals, and so on. In conventional ALD, the source and reactant are pulsed into the reaction chamber alternately, one at a time, separated by purging or evacuation periods. Thermal ALD and metal organic ALD are also used, but these have their own advantages and disadvantages. Furthermore, plasma-enhanced ALD has come into the spotlight because it has more freedom in processing conditions; it uses highly reactive radicals and ions and for a wider range of material properties than the conventional thermal ALD, which uses $H_2O$ and $O_3$ as an oxygen reactant. However, the throughput is still a challenge for a current time divided ALD system. Therefore, a new concept of ALD, fast ALD or spatial ALD, which separate half-reactions spatially, has been extensively under development. In this paper, we reviewed these various kinds of ALD equipment, possible materials using ALD, and recent ALD research applications mainly focused on materials required in microelectronics.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.463-466
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• 2013

We examined relationship between rainfall and triggering of shallow landslides in South Korea, based on hourly rainfall data for 478 shallow landslides during 1963-2012. Rainfall intensity(I) and duration(D) relationship was analyzed to obtain the I-D threshold for the initiation of a shallow landslide using the quantile regression analysis. The I-D threshold equation from in this study is: $I=9.64D^{-0.27}$($4{\leq}D{\leq}76$), where I and D are expressed in millimeters per hour and hours, respectively. In addition, rainfall criteria were proposed to predict the potential to cause landslides, based on values of I-D and cumulative rainfall derived from quantile regression analysis. Our findings may provide essential data and important evidences for the improvement of landslide warning and evacuation system.

• Fire Science and Engineering
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• v.30 no.6
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• pp.118-123
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• 2016

In the event of a building fire, it is important to control the smoke generated to ensure the safe evacuation of occupants. A natural smoke ventilator should be installed to exhaust the fire smoke in accordance with the Korean building Act and Code. On the other hand, the present law does not specify the contents regarding natural smoke ventilators sufficiently. The problems that occur in various parts, such as the installation target, installation location, free area, and the control and maintenance of natural smoke ventilators need to be solved. In this study, the problem of the current system was examined through domestic and foreign standards, preliminary research, and field investigations. In addition, suggestions for improvement are provided.