• Tunnel and Underground Space
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• v.24 no.4
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• pp.275-281
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• 2014

The performance criteria of rockfall protection fence and reliability index were investigated considering characteristic of rockfall energy occurred at 160 cut slopes in national highway. As a result of study on statistic of variables that decide rockfall energy using Monte-Carlo simulation, the degree of slope was normal distribution type, mass of rockfall and height of slope was lognormal distribution type. The rockfall energy follows lognormal distribution because of statistical characteristic of mass of rockfall. The reliability index of rockfall protection fence was 0.678 and the failure probability of was very high as 24.9%. Proposed performance criteria of rockfall protection fence considering the scale of domestic rockfall energy is maximum 500 kJ and the range of reliability index was from 1.028 to 1.956. the failure probability of rockfall protection fence was from 14.8 to 2.5 percent if applying the performance criteria using the reliability index.

• Journal of Korean Society of Steel Construction
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• v.17 no.3 s.76
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• pp.263-270
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• 2005

This paper presents a program for protecting vehicles against side winds on highways. The present study consists of three processes. The first one involves giving a guideline for evaluating driving safety in high winds. The second one involves making a guideline for determining the necessity of wind protection system for a certain road area. A reasonable procedure is suggested based on the probability model of wind data on weather stations and the correction of local topographical conditions. The third one involves design of wind barriers. Both CFD analyses and wind tunnel tests were performed to find the proper type of wind barrier considering vehicle controllability, structural safety, economical efficiency as well as driver's visibility. Performance of the designed wind fences was verified from field tests. The performance of the four different types of wind barrier installed at the elevated bridge were tested and some of the results were provided.

• Wind and Structures
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• v.34 no.3
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• pp.275-290
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• 2022

Mobile sand barriers are a new type sand-retaining structure that can be moved and arranged according to the engineering demands of sand control. When only used for sand trapping, mobile sand barriers could be arranged in single row. For the dual purposes of sand trapping and sand stabilization, four rows of mobile sand barriers can be arranged in a staggered form. To reveal the effect of plane layout, the included angle between sand barrier direction and wind direction on the characteristics of flow fields and the sand control laws of mobile sand barriers, numerical computations and wind tunnel tests were conducted. The results showed that inflows deflected after passing through staggered arrangement sand barriers due to changes in included angle, and the sand barrier combination exerted successive wind resistance and group blocking effects. An analysis of wind resistance efficiency revealed that the effective protection length of staggered arrangement sand barriers approximately ranged from the sand barrier to 10H on the leeward side (H is sand barrier height), and that the effective protection length of single row sand barriers roughly ranged from 1H on the windward side to 20H on the leeward side. The distribution of sand deposit indicated that the sand interception increased with increasing included angle in staggered arrangement. The wind-breaking and sand-trapping effects were optimal when included angle between sand barrier direction and wind direction is 60°-90°.

• Journal of the Society of Disaster Information
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• v.20 no.1
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• pp.82-92
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• 2024

Purpose: The purpose of this study is to find a solution to the massive data construction that occurs when fire simulation data is linked to augmented reality and the resulting data overload problem. Method: An experiment was conducted to set the interval between appropriate input data to improve the reliability and computational complexity of Linear Interpolation, a data estimation technology. In addition, a validity verification was conducted to confirm whether Linear Interpolation well reflected the dynamic changes of fire. Result: As a result of application to the underground common area, which is the study target building, it showed high satisfaction in improving the reliability of Interpolation and the operation processing speed of simulation when data was input at intervals of 10 m. In addition, it was verified through evaluation using MAE and R-Squared that the estimation method of fire simulation data using the Interpolation technique had high explanatory power and reliability. Conclusion: This study solved the data overload problem caused by applying digital twin technology to fire simulation through Interpolation techniques, and confirmed that fire information prediction and visualization were of great help in real-time fire prevention.

• Fire Science and Engineering
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• v.15 no.1
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• pp.23-33
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• 2001

The utility tunnels are the important facility as a mainstay of country because of the latest communication developments. However, the utilities tunnel is difficult to deal with in case of a fire accident. When a cable burns, the black smoke containing poisonous gas will be reduced. This black smoke goes into the tunnel, and makes it difficult to extinguish the fire. Therefore, when there was a fire in the utility tunnel, the central nerves of the country had been paralyzed, such as property damage, communication interruption, in addition to inconvenience for people. This paper is based on the fire occurred in the past, and reenacting the fire by making the real utilities tunnel model. The aim of this paper is the scientific analysis of the character image of the fire, and the verification of each fire protection system whether it works well after process of setting up a fire protection system in the utilities tunnel at a constant temperature. The fire experiment was equipped with the linear heat detector, the fire door, the connection water spray system and the ventilation system in the utilities tunnel. Fixed portion of an electric power supply cable was coated with a fire retardant coating, and a heating tube was covered with a fireproof. The result showed that the highest temperature was $932^{\circ}c$ and the linear heat detector was working at the constant temperature, and it pointed at the place of the fire on the receiving board, and Fixed portion of the electric power supply cable coated with the fire retardant coating did not work as the fireproof. The heating tube was covered with the fireproof about 30 minutes.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.1
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• pp.167-175
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• 2019

To effectively deal with the fire in tunnel which is mostly the vehicle fire, it's more important to suppress the fire at early stage. In urban tunnel, however, accessibility to the scene of fire by the fire fighter is very limited due to severe traffic congestion which causes the difficulty with firefighting activity in timely manner and such a problem would be further worsened in underground road (double-deck tunnel) which has been increasingly extended and deepened. In preparation for the disaster in Korea, the range of life safety facilities for installation is defined based on category of the extension and fire protection referring to risk hazard index which is determined depending on tunnel length and conditions, and particularly to directly deal with the tunnel fire, fire extinguisher, indoor hydrant and sprinkler are designated as the mandatory facilities depending on category. But such fire extinguishing installations are found inappropriate functionally and technically and thus the measure to improve the system needs to be taken. Particularly in a double-deck tunnel which accommodates the traffic in both directions within a single tunnel of which section is divided by intermediate slab, the facility or the system which functions more rapidly and effectively is more than important. This study, thus, is intended to supplement the problems with existing tunnel life safety system (fire extinguishing) and develop the remote-controlled automatic fire extinguishing system which is optimized for a double-deck tunnel. Consequently, the system considering low floor height and extended length as well as indoor hydrant for a wide range of use have been developed together with the performance verification and the process for commercialization before applying to the tunnel is underway now.

• Journal of computational fluids engineering
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• v.17 no.2
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• pp.100-106
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• 2012

Ice accretion on the surface of aircraft in flight can adversely affect the safety of aircraft. In particular, it can cause degradation of critical aircraft performances such as maximum lift coefficient and total pressure recovery factor in engine air intake. In this study, computational prediction of ice accretion around a rotorcraft air intake is conducted in order to identify the impingement region with high droplet collection efficiency. Then the amount of ice accretion on the air intake, which is essential in determining the required power of ice protection system, is calculated. Finally, the effect of icing wind tunnel size is investigated in order to check the compatibility with the real in-flight test environment.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.151-156
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• 2008

The after 1974 capital region electric railroad is opened to traffic Koraill and Seoul metro adopt each other different power supply method and they operate and they are come. AC 25[kv] method voltage the insulation becomes larger standing distance highly, the case tunnel section which will introduce in the underground segment becomes on a large scale and the cost of construction increases to the city center and the underground segment adoption of DC method was many. To recent times with R-bar (Rigid-bar) introductions change of tunnel section the introduction of AC method came to be easy without in the underground segment. Operates sees in the electric protection where the Seoul metro and the Korail are different each other and, from the dead section segment the interior electric light to put out lights the passenger brings about inconveniently and the civil appeal which demands a power supply method unification occurs, within the company interchange electric railroad brazier safety improvement and maintenance expense curtailment etc. the flaw is original proposal, is a condition which finishes a feasibility study service about the power supply method fringe land. Interchange analysis of the DC electric railway it leads from the present paper and it compares under analyzing being it could be reflected to also the route which is in the process of actual using boil the strong point and a weak point of DC and AC method of the establishment route constructive at the time of and

• Fire Science and Engineering
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• v.23 no.4
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• pp.13-18
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• 2009

The main objective of the present study is to investigate smoke propagation in railway tunnels with rescue stations. In particular, based on measurement of HRR (heat release rate) for pool fires formed at different locations, the influence of fire source location on smoke behavior is examined. The fuel is n-heptane and pool fires are generated with a square length 4cm. With the use of MVHS (Modified Volumetric Heat Source) model for fire source, extensive numerical simulations are performed by using the commercial code FLUENT (Ver.6.3) Predicted smoke temperatures and smoke propagation are discussed. From numerical predictions, it is found that ventilation systems may be necessary in the railway tunnels because the smoke moves along the tunnel, and consequently it enters the non-accident tunnel. It is also confirmed that the cross-passage and fire protection wall systems contribute to control the smoke.

• Archives of Reconstructive Microsurgery
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• v.17 no.1
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• pp.36-41
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• 2008

Surgical treatment of compressive ulnar neuropathy at the elbow has been performed with a wide variety of techniques. Among these techniques, anterior submuscular transposition of the ulnar nerve has been regarded as the method of choice by many authors. It has many advantages including a low recurrence rate, scar-free vascular bed, and protection from repeated trauma to the nerve. However, anterior submuscular transposition is technically demanding and requires more extensive soft tissue dissection. On the other hand, anterior subfascial transposition is less invasive, requires a relatively shorter operation time than the submuscular technique, and also can be done safely even in patiensts with elbow arthritis. We evaluated the clinical results of anterior submuscular transposition compared with anterior subfascial transposition. Fifteen patients underwent anterior submuscular transposition and ten patients underwent anterior subfascial transposition of the ulnar nerve. The mean follow-up time was 15 months (range 10 to 38 months) in the anterior submuscular transposition group and 7 months (range 6 to 15 months) in the anterior subfascial transposition group. According to the outcome status determination algorithm devised by Mowlavi, 3 patients (20%) showed total relief, 10 patiensts (66.7%) improvement and 2 patients (13.3%) no changes in the anterior submuscular transposition group. In the anterior subfascial transposition group, 2 patients (20%) showed total relief, 7 patients (70%) improvement and 1 patient (10%) displayed no changes. Statistically there was no significant difference of the clinical results between the two surgical techniques. Therefore we would suggest anterior subfascial transposition of the ulnar nerve as a preferred method for treatment of cubital tunnel syndrome.