• Korean Journal of Remote Sensing
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• v.34 no.1
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• pp.75-87
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• 2018

The Baekdu volcano (2,750 m a.s.l.) is located on the border between Yanggando Province in North Korea and Jilin Province in China. Its eruption in 946 A.D. was among the largest and most violent eruptions in the past 5,000 years, with a volcanic explosivity index (VEI) of 7. In this study, we processed and analyzed lahar-inundation hazard zone data, applying a geographic information system program with menu-driven software (LAHARZ)to a shuttle radar topography mission 30 m digital elevation model. LAHARZ can simulate inundation hazard zones created by large lahar flows that originate on volcano flanks using simple input parameters. The LAHARZ is useful both for mapping hazard zones and estimating the extent of damage due to active volcanic eruption. These results can be used to establish evacuation plans for nearby residents without field survey data. We applied two different simulation methods in LAHARZ to examine six water systems near Baekdu volcano, selecting weighting factors by varying the ratio of height and distance. There was a slight difference between uniform and non-uniform ratio changes in the lahar-inundation hazard zone maps, particularly as slopes changed on the east and west sides of the Baekdu volcano. This result can be used to improve monitoring of volcanic eruption hazard zones and prevent disasters due to large lahar flows.

• Fire Science and Engineering
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• v.27 no.2
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• pp.46-53
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• 2013

The architecture environment has changed. The corresponding design criteria should be changed. From July 27th, 2005 the Korea Standard of the fire door changed concerning the smoke resistance test which made the door gap structure more elaborate. However the National Fire Safety Codes are applied by the old data's of England. Which in case differs in the actual construction to the blue print, making the safety standard too excessive. Analyze the results and the phenomenon that occurs due to the difference between design and reality. The National Fire Safety Codes should be revised to leakage crack calculation is presented. Difference of the air flow for the smoke protection due to the stack effect analyzed. Living patterns and evacuation patterns of the apartment reflect and reasonable air flow measurement method are presented.

• Fire Science and Engineering
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• v.31 no.3
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• pp.88-96
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• 2017

The subway can transport a lot of people at a certain route at once, and the railway and the platform are underground, so it is advantageous to use the ground space efficiently. But If a fire occurs in a subway that is used by an unspecified number of people, such as the Daegu Subway Fire Disaster, many casualties can occur. As a result of the previous research, it was confirmed that the performance of the ventilation system of the old subway platform was remarkably degraded. Therefore, in this study, based on the experimental results of the previous research, we confirmed the flow of the hot and CO flows according to the ventilation mode in the case of fire by three - dimensional numerical analysis. As a result, it was found that the old ventilation system could not maintain the hot air temperature below the reference value for 4 minutes based on the evacuation time of the platform, and when the ventilation performance was enhanced by adding Oversized Exhaust Ports at the upper part of the platform, And the temperature of the heat flow can be maintained.

• Tunnel and Underground Space
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• v.7 no.2
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• pp.100-107
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• 1997

In case of a fire outbreak in a uni-directional road tunnel, the flow of traffic immediately behind the fire disaster will be stalled all the way back to the entrance of the tunnel. Furthermore, when the vehicle passengers try to flee away from the fire toward the entrance of the tunnel, the extremely hot fume that propagates in the same direction will be fatal to the multitudes evacuating, but may also cause damage to the ventilation equipments and the vehicles, compounding the evacuation process. This paper will present the 3-dimensional modelling analysis of the preventive measures of such a fume propagation in the same direction as the evacuating passengers. For the analysis, the fire hazard was assumed to be a perfect combustion of methane gas injected through the 1 m X 2 m nozzle in the middle of the tunnel, and the product of $CO_2$ as the indicator of the fume propagation. From the research results, when the fire hazard occurred in middle of the 400 m road tunnel, the air density decreased around the fire point, and the maximum temperatures were 996 K and 499 K at 210 m and 350 m locations, respectively, 60 seconds after fire disaster occurred, when the fumes were driven out only towards the exit-direction of the tunnel. By tracing the increase of $CO_2$ level over 1% mole fraction, the minimum longitudinal ventilation velocity was found to be 2.40 m/sec. Furthermore, through Analysis of the temperature distribution graphs, and observation of the cross-sectional distribution of $CO_2$ over 1% mole fraction, it was found that the fume did not mix with the air, but rather moved far in a laminar flow towards exit of the tunnel.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.6
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• pp.869-876
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• 2008

A thermocompressor is the equipment which compresses a vapor to a desired discharge pressure. Since it was first used as the evacuation pump for a surface condenser, it has been widely adopted for energy saving systems due to its high working confidence. In the present study, the geometrical analysis of the shape between the jet nozzle and the diffuser inlet, the drag force was calculated by means of the integrated equation of motion and the computational fluid dynamic (CFD) package called FLUENT. The computer simulations were performed to investigate the effects by the various suction flow rates, the distance from jet nozzle outlet to the diffuser inlet and the dimensions of the diffuser inlet section through the iterative calculation. In addition, the results from the CFD analysis on the thermocompressor and the experiments were compared for the verification of the CFD results. In the case of a jet nozzle, the results from the CFD analysis showed a good agreement with the experimental results. Furthermore, in this study, a special attention was paid on the performance of the thermocompressor by varying the diffuser convergence angle of $0.0^{\circ}$, $0.5^{\circ}$, $1.0^{\circ}$, $2.0^{\circ}$, $3.5^{\circ}$ and $4.5^{\circ}$. With the increase of the diffuser convergence angle. the suction capacity was improved up to the degree of $1.0^{\circ}$ while it was decreased over the degree of $1.0^{\circ}$.

• Journal of Trauma and Injury
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• v.26 no.3
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• pp.248-251
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• 2013

Introduction: A post-traumatic mesenteric arteriovenous fistula (AVF) is extremely rare. Case Report: A previously healthy 26-year-old male was injured with an abdominal stab wound. Computed tomography (CT) showed liver injury, pancreas injury and a retropancreatic hematoma. We performed the hemostasis of the bleeding due to the liver injury, a distal pancreatectomy with splenectomy and evacuation of the retropancreatic hematoma. On the 5th postoperative day, an abdominal bruit and thrill was detected. CT and angiography showed an AVF between the superior mesenteric artery (SMA) and the inferior mesenteric vein with early enhancement of the portal vein (PV). The point of the AVF was about 4 cm from the SMA's orifice. After an emergent laparotomy and inframesocolic approach, the isolation of the SMA was performed by dissection and ligation of adjacent mesenteric tissues which was about 6 cm length from the nearby SMA orifice, preserving the major side branches of the SMA, because the exact point of the AVF could not be identified despite the shunt flow in the PV being audible during an intraoperative hand-held Doppler-shift measurement. After that, the shunt flow could not be detected by using an intraoperative hand-held Doppler-shift measuring device. CT two and a half months later showed no AVF. There were no major complications during a 19-month follow-up period. Conclusion: Early management of a post-traumatic mesenteric AVF is essential to avoid complications such as hemorrhage, congestive heart failure and portal hypertension.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1018-1021
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• 2006

Powdered metal parts and components may be carburized successfully in a vacuum furnace by combining carburizing technology $VacCarb^{TM}$ with a hi-tech control system. This approach is different from traditional carburizing methods, because vacuum carburizing is a non-equilibrium process. It is not possible to set the carbon potential as in a traditional carburizing atmosphere and control its composition in order to obtain a desired carburized case. This paper presents test results that demonstrate that vacuum carburizing system $VacCarb^{TM}$ carburized P.M. materials faster than traditional steel with acceptable results. In the experiments conducted, PM samples with the lowest density and open porosity showed a dramatic increase in the surface carbon content up to 2.5%C and a 3 times deeper case. Currently the boost-diffusion technique is applied to control the surface carbon content and distribution in the case. In the first boost step, the flow of the carburizing gas has to be sufficient to saturate the austenite, while avoiding soot deposition and formation of massive carbides. To accomplish this goal, the proper gas flow rate has to be calculated. In the case of P.M. parts, more carbon can be absorbed by the part's surface because of the additional internal surface area created by pores present in the carburized case. This amount will depend on the density of the part, the densification grade of the surface layer and the stage of the surface. "as machined" or "as sintered". It is believed that enhanced gas diffusion after initial evacuation of the P.M. parts leads to faster carburization from within the pores, especially when pores are open . surface "as sintered" and interconnected . low density. A serious problem with vacuum carburizing is delivery of the carbon in a uniform manner to the work pieces. This led to the development of the different methods of carburizing gas circulation such as the pulse/pump method or the pulse/pause technique applied in SECO/WARWICK's $VacCarb^{TM}$ Technology. In both cases, each pressure change may deliver fresh carburizing atmosphere into the pores and leads to faster carburization from within the pores. Since today's control of vacuum carburizing is based largely on empirical results, presented experiments may lead to better understanding and improved control of the process.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.195-195
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• 2016

Kon - Ha Thanh River basin is the largest and the most important river basin in Binh Dinh, a province in the South Central Coast of Vietnam. In the lower rivers, frequent flooding and inundation caused by heavy rains, upstream flood and or uncontrolled flood released from upstream reservoirs, are very serious, causing damage to agriculture, socio-economic activity, human livelihood, property and lives. The damage is expected to increase in the future as a result of climate change. An advanced flood warning system could provide achievable non-structural measures for reducing such damages. In this study, we applied a modelling system which intergrates a 1-D river flow model and a 2-D surface flow model for simulating hydrodynamic flows in the river system and floodplain inundation. In the model, exchange of flows between the river and surface floodplain is calculated through established links, which determine the overflow from river nodes to surface grids or vice versa. These occur due to overtopping or failure of the levee when water height surpasses levee height. A GIS based comprehensive raster database of different spatial data layers was prepared and used in the model that incorporated detailed information about urban terrain features like embankments, roads, bridges, culverts, etc. in the simulation. The model calibration and validation were made using observed data in some gauging stations and flood extents in the floodplain. This research serves as an example how advanced modelling combined with GIS data can be used to support the development of efficient strategies for flood emergency and evacuation but also for designing flood mitigation measures.

• Journal of Korea Water Resources Association
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• v.56 no.11
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• pp.775-784
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• 2023

With the increasing trend of extreme rainfall that exceeds the design frequency of man-made structures due to extreme weather, it is necessary to review the safety of agricultural reservoirs designed in the past. However, there are no local government-managed reservoirs (13,685) that can be discharged in an emergency, except for reservoirs over a certain size under the jurisdiction of the Korea Rural Affairs Corporation. In this case, it is important to quickly deploy a mobile siphon to the site for preliminary discharge, and this study evaluated the applicability of a mobile siphon with a diameter of 200 mm, a minimum water level difference of 6 m, 420 (m²/h), and 10,000 (m²/day), which can perform both preliminary and emergency discharge functions, to the Yugum Reservoir in Gyeongju City. The test bed, Yugum Reservoir, is a facility that was completed in 1945 and has been in use for about 78 years. According to the hydrological stability analysis, the lowest height of the current dam crest section is 27.15 (EL.m), which is 0.29m lower than the reviewed flood level of 27.44 (EL.m), indicating that there is a possibility of lunar flow through the embankment, and the headroom is insufficient by 1.72 m, so it was reviewed as not securing hydrological safety. The water level-volume curve was arbitrarily derived because it was difficult to clearly establish the water level-flow relationship curve of the reservoir since the water level-flow measurement was not carried out regularly, and based on the derived curve, the algorithm for operating small and medium-sized old reservoirs was developed to consider the pre-discharge time, the amount of spillway discharge, and to predict the reservoir lunar flow time according to the flood volume by frequency, thereby securing evacuation time in advance and reducing the risk of collapse. Based on one row of 200 mm diameter mobile siphons, the optimal pre-discharge time to secure evacuation time (about 1 hour) while maintaining 80% of the upper limit water level (about 30,000 m²) during a 30-year flood was analyzed to be 12 hours earlier. If the pre-discharge technology utilizing siphons for small and medium-sized old reservoirs and the algorithm for reservoir operation are implemented in advance in case of abnormal weather and the decision-making of managers is supported, it is possible to secure the safety of residents in the risk area of reservoir collapse, resolve the anxiety of residents through the establishment of a support system for evacuating residents, and reduce risk factors by providing risk avoidance measures in the event of a reservoir risk situation.

• Fire Science and Engineering
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• v.28 no.1
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• pp.37-43
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• 2014

The high predictive performance of fire detector models is essentially needed to assure the reliability of fire and evacuation modeling in the process of Performance-Based fire safety Design (PBD). The main objective of the present study is to measure input information in order to predictive the accurate activation time of fixed temperature heat detectors adopted in Fire Dynamics Simulator (FDS) as a representative fire model. To end this, Fire Detector Evaluator (FDE) which could be measured the device properties of detector was used, and the spot-type fixed temperature heat detectors of two thermistor types and one bimetal type were considered as research objectors. Activation temperature and Response Time Index (RTI) of detectors required for the fire modeling were measured, and then the RTI was measured for ceiling jet flow and vertical jet flow in consideration of the install location of detectors. The results of fire modeling using measured device properties were compared and validated with the experimental results of full-scale compartment fires. It was confirmed that, in result, the numerically predicted activation time of detector showed reasonable agreement with the measured activation time.