• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.29-39
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• 2017

In this research, thermal design data such as heat transfer coefficient on the wall surface required for ventilation system design which is to prevent the temperature rise in the underground utility tunnel that three sides are adjoined with the ground was investigated in numerical analalysis. The numerical model has been devised including the tunnel lining of the underground utility tunnel in order to take account for the heat transfer in the tunnel walls. The air temperature in the tunnel, wall temperature, and the heating value through the wall based on heating value(117~468 kW/km) of the power cable installed in the tunnel and the wind speed in the tunnel(0.5~4.0 m/s) were calculated by CFD simulation. In addition, the wall heat transfer coefficient was computed from the results analysis, and the limit distance used to keep the air temperature in the tunnel stable was examined through the research. The convective heat transfer coefficient at the wall surface shows unstable pattern at the inlet area. However, it converges to a constant value beyond approximately 100 meter. The tunnel wall heat transfer coefficient is $3.1{\sim}9.16W/m^2^{\circ}C$ depending on the wind speed, and following is the dimensionless number:$Nu=1.081Re^{0.4927}({\mu}/{\mu}_w)^{0.14}$. This study has suggested the prediction model of temperature in the tunnel based on the thermal resistance analysis technique, and it is appraised that deviation can be used in the range of 3% estimation.

• Journal of the Korean Institute of Gas
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• v.27 no.4
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• pp.102-109
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• 2023

In realizing a hydrogen society, it is important to secure the safety of the hydrogen refueling station, which is the facility where consumers can easily meet hydrogen. The hydrogen refueling station consists of compressed gas facilities that store high-pressure hydrogen, and there is a risk that the high-pressure compressed gas facility will rupture due to a fire explosion due to hydrogen leakage in the facility or the influence of surrounding fires. Accordingly, the Korea Gas Safety Corporation is making every effort to find out risk factors from the installation stage, reflect them in the design, and secure safety through legal inspection. In this study, a TNT explosion demonstration test using a protection wall was conducted to confirm the safety effect of the protection wall installed at the hydrogen refueling station, and the empirical test results were compared and verified using FLACS-CFD, a CFD program. As a result of the empirical test and CFD analysis, it was confirmed that the effect of reducing the explosion over-pressure at the rear end of the protection wall decreased from 50% to up to 90% depending on the location, but the effect decreased when it exceeded a certain distance. The results of the empirical test and computer analysis for verifying the safety of the protection wall will be used in proposals for optimizing the protection wall standards in the future.

• Journal of the Korean Institute of Rural Architecture
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• v.10 no.3
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• pp.59-66
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• 2008

This study was performed to ascertain how HyangGyos based on national ideology were built in Jeju Island and what their detailed styles are. In Jeju-HyangGyo, unique architectural characteristics are shown as they have been built in an island independent from the mainland. Also up-down system was well reflected in detailed architectural styles. The main temple of Jeju-HyangGyo was built in the type of one-Chulmok(a subsidiary material of Gongpo and a piece of wood to support the eaves) of which ancon supports a purline from the center of a pillar and two-Ikgong(a piece of wood engraved to put on an ancon), but in the case of the lecture hall, its Gongpo(a piece of wood to support the eaves) was inferior in quality. In the case of Jeju abutments were used in main temples and fire walls were mostly used. In particular, their abutments are difficult to be observed in HyangGyo in the mainland. It is presumed that the abutment and the fire wall used in Jeju Island might be the best solution to protect structures from rain and moisture. To sum up, local characteristics and traditional rules were thoroughly reflected in Jeju-HyangGyos built in Jeju Island from the aspect of arrangement and detailed style. In conclusion, it is significant that architectural styles, not to mention the other aspects of Jeju culture, were suitably adapted to Jeju Island.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.67-72
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• 2005

This study is intended to examine the effect of photoluminescent exit path markings in the event of failure of both the power and back-up power to the lighting and illuminated exit sign. To achieve the purpose, the test house was exhibited in Fire EXPO '05. 520 visitors were examined from May 26-29, 2005. The results of this study are as follows; The evacuation from buildings in dark conditions showed that 70% of men and 72% of women were crawled along the wall. Meanwhile, 88% of men and 83% of women were evacuated with ordinary walking in photoluminescent exit path markings. The photoluminescent exit path markings located on public buildings floors will aid in evacuation from buildings in the event of failure of the power to the lightings and illuminated exit signs.

• Fire Science and Engineering
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• v.8 no.1
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• pp.9-20
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• 1994

To understand the phenomena of laminar diffusion flame along vortical walt, the numerical analysis has been performed. Keller-box method was used to solve the problem in the boundary layer. The governing equation is simplified by thin-flame approxiamtion. And energy and chemical species equations are normalized with Schvab-Zeldovich variables. A physical domain is divided the boundary layer along streamwise coordinate as the combustion region and the propagation region. And Radiation model is concerned in these region. As a result, typical phenomena have been observed. Comparison of the numerical results with experimental data shows that the present method can successfully predict phenomena of laminar diffusion flame along upright surface.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.3
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• pp.243-250
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• 2019

In this study, to ensure the safety of the packaged hydrogen refueling system, the improvement plan was derived by using 3-dimensional CFD program (FLACS). We also confirmed the effectiveness of risk reduction and the suitability of safety standard. By ventilation performance evaluation according to the position of the vent, it demonstrated that the vent should be installed at the ceiling to safely ventilate without stagnation of the leaked gas. In case of ventilation system according to KGS standard, risk situation could be resolved after about 5 minutes in the worst leaked condition. The result showed that jet fire and explosion inside the packaged system could affect the surrounding facilities. This proves that the standard for installing flame detectors, emergency shut down system and protection wall is appropriate.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.05a
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• pp.295-296
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• 2021

With the recent diversification and complication of buildings, the functions of building are also developing. As much as the development of buildings, the machine or equipment used for them is also developing. Thus, all sorts of domestic/foreign industrial facilities and fire stations in the whole nation are using the electric shutter that could meet the insulation just like the exterior wall of general buildings, for bringing-in/storage and crime prevention/fire prevention. Currently, various types of electric shutters are used. Such wrong operation and poor management are causing many panel-falling accidents. This study researched the reduction of electric shutter panel-falling risk by reviewing the domestic/foreign laws and standards, and researching the new safety equipment. First, the causes for falling and accident types were drawn by analyzing the cases of electric shutter accidents. After that, a checklist as the measures for reducing the falling of electric shutter in building was suggested by analyzing the items for the inspection of electric shutter.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.27-28
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• 2023

Currently, the Off-Site Construction (OSC) construction method, which emphasizes the minimization of field work, is being emphasized at construction sites due to the lack of construction skilled manpower, extreme weather, and the Severe Disaster Punishment Act. In this study, we developed a stacked PC modular, which is a method of stacking PC modules, and solved the lifting problem by reducing the weight of the unit module, which is emerging as the biggest disadvantage of PC modules, to around 20 tons. For the connection between modules, structural safety was secured through repeated history tests of the wall and slab connection. Walls and slabs satisfied all statutory fire resistance times through fire resistance tests, and residential performance was evaluated to be satisfactory through mock-up demonstration. The developed PC modular has been applied to the construction of commercial houses, detached houses, shopping malls, churches, etc., and has design results for many buildings such as dormitories, detached houses with 4 floors or more, and resorts, so it is expected that an atmosphere of revitalization of construction methods will be created.

• Journal of Astronomy and Space Sciences
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• v.28 no.3
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• pp.233-239
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• 2011

A series of computational analyses was performed to predict the cooling process by the cooling channel of preburners used for kerosene-liquid oxygen staged combustion cycle rocket engines. As an oxygen-rich combustion occurs in the kerosene fueled preburner, it is of great importance to control the wall temperature so that it does not exceed the critical temperature. However, since the heat transfer is proportional to the speed of fluid running inside the channel, the high heat transfer leads to a trade-off of pressure loss. For this reason, it is necessary to establish a certain criteria between the pressure loss and the heat transfer or the wall surface temperature. The design factors of the cooling channel were determined by the computational research, and a test model was manufactured. The test model was used for the hot fire tests to prove the function of the cooling mechanism, among other purposes.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.382-388
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• 2017

In this study, a basic study was carried out on the external strengthening method of public buildings. A steel damper is installed outside the specimen with a rocking wall and connected to the frame. Two specimens were fabricated, and the non-reinforced specimens utilized the existing results. As a result of evaluating the envelope curve, strength, stiffness and energy dissipation capacity, it was evaluated that the strength enhancement of the RW_P specimen externally reinforced plate damper was evaluated to be excellent. In addition, RW_S specimens with external S type damper shows a gentle envelop curve after maximum load, and it can be confirmed that the damper properly dissipates the seismic energy.