• Fire Science and Engineering
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• v.22 no.3
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• pp.216-220
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• 2008

Water mist fire suppression system utilizes the fire suppression features such as cooling of fire source, dilution of ambient oxygen, and shielding of radiation heat with the evaporation of microscopic water droplets. The momentum of water mist is relatively lower than that of larger water droplet and the infiltration of water mist to the fire source is not effective. Contribution of evaporated water vapor is liable to decline to limited portion of fire source due to its light weight and sparse density. On the other hand, the cycling water mist pattern is expected to improve the penetration force of water mist as well as the air expelling capability with the stratified spray characteristics. At this paper, we present the analyzed fire suppression capability of intermittent water spray pattern by use of FDS which is computational fire dynamics fire model. We expect this analysis can support the basic concept to the development of the prototype of water mist nozzle.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1257-1264
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• 2011

This paper presents 3D simulation by STAR-CCM+ for lean premixed combustion in a stationary gas turbine combustor with separate pilot and main nozzles. The constant for the source term in the flame area density transport equation was modified to account for a low global equivalence ratio and validated against measurement data. A Partially-premixed Coherent Flame Model(PCFM) involves propagation of a laminar premixed flame with the predicted flame surface density and equilibrium assumption in the burned gas with spatial inhomogeneity. The conditions for cooling by radiation and convection are considered for accurate determination of the heat flux on the wall. A parametric study is of the pilot-fuel-to-total-fuel-ratio is carried out. A chemical reactor network (CRN) was constructed on the basis of the 3D simulation results and compared against measurements of NOx.

• Transactions of the KSME C: Technology and Education
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• v.2 no.1
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• pp.57-63
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• 2014

In this paper new air-cooling system utilizing Stirling engine was proposed for improving efficiency in solar photovoltaic power generation. The solar cell plate was equipped with semi-circular channel for air flow on the backside. Beta-type Stirling engine was installed on the plate and its flywheel was connected to a motor fan by a transmission belt. A forced convective air flow for heat radiation was generated by the operation of the self-starting Stirling engine. The performance tests for power generation of solar cell with or without the proposed air-cooling system were conducted under halogen lamp. From the experimental results, it was found that decline in output voltage of the solar cell with proposed cooling system was 25% less than that of the solar cell without cooling system.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• v.1 no.1
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• pp.35-43
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• 1997

Handling the emergency problems such as Chemobyl accident require real time prediction of pollutants dispersion. One-point real time sounding at pollutant source and simple model including turbulent-radiation process are very important to predict dispersion at real time. The stability categories obtained by one-dimensional numerical model (including PBL dynamics and radiative process) are good agreement with observational data (Golder, 1972). Therefore, the meteorological parameters (thermal, moisture and momentum fluxes; sensible and latent heat; Monin-Obukhov length and bulk Richardson number; vertical diffusion coefficient and TKE; mixing height) calculated by this model will be useful to understand the structure of stable boundary layer and to handling the emergency problems such as dangerous gasses accident. Especially, this simple model has strong merit for practical dispersion models which require turbulence process but does not takes long time to real predictions. According to the results of this model, the urban area has stronger vertical dispersion and weaker horizontal dispersion than rural area during daytime in summer season. The maximum stability class of urban area and rural area are 'A' and 'B' at 14 LST, respectively. After 20 LST, both urban and rural area have weak vertical dispersion, but they have strong horizontal dispersion. Generally, the urban area have larger radius of horizontal dispersion than rural area. Considering the resolution and time consuming problems of three dimensional grid model, one-dimensional model with one-point real sounding have strong merit for practical dispersion model.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.12
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• pp.786-790
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• 2016

Hole explosion behaviors were observed during drilling fine holes with laser beam on the LTCC green bar of $320{\mu}m$ thick after lamination of green sheets prepared by tape casting of thick film process. The incidence of these hole explosions was inversely proportional to hole sizes. The incidence of hole explosion was 20 % number of hole with the size of $60{\mu}m$ exploded for the UV radiation, while the explosion did not appear for hole sizes over $100{\mu}m$. To prevent hole explosion behavior during laser-drilling of fine holes, carbon black powder was added as an additive in the LTCC composition, which has superior thermal durability. As a consequence, hole explosion rate was suppressed to 0.8 % for the hole size of $50{\mu}m$ green sheet with the carbon black amount of 10 weight % and the laser power of 3 watt. Added carbon is thought to reduce the heat-affected region during laser drilling.

• Journal of electromagnetic engineering and science
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• v.14 no.3
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• pp.267-272
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• 2014

Hyperthermia is a form of cancer treatment in which affected human tissue is exposed to $>40^{\circ}C$ temperature. In this paper, our goal is to assess the efficacy of fullerene agents to reduce heating time for cancer treatment. Such agents can accelerate heating of cancer cells and improve hyperthermia treatment efficacy. Typically, in vitro testing involves cancer cell culturing, heating cell cultures in accordance to specifications, and recording cancer cell viability after hyperthermia. To heat cell cultures, we design and evaluate a 2.4-GHz microwave cavity with controllable temperature. The cavity is comprised of a polystyrene cell culture dish (diameter = 54 mm, height = 13.5 mm) and a printed monopole antenna placed within the cavity for microwave heating. The culture temperature can be controlled through the intensity and duration of the antenna's microwave radiation. Heating experiments were carried out to validate the cavity's performance for F-12K culture medium (Kaighn's F-12K medium, ATCC). Importantly, fullerene agents were shown to reduce heating time and improve hyperthermia treatment efficacy. The culture medium temperature increased, on average, from $24.0^{\circ}C$ to $50.9^{\circ}C$ (without fullerene) and from $24.0^{\circ}C$ to $56.8^{\circ}C$ (with 3 mg/mL fullerene) within 15 minutes.

• Fire Science and Engineering
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• v.31 no.4
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• pp.1-6
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• 2017

A fire resistance certification needs to be obtained before fire protection paint can be used in Korea. In the case of paint, the tests for certification are fire, gas hazard and bond strength. According to the hazard test standard of combustion gas, 16 mice are sacrificed every test. Therefore, there are ethical problems for the experimenter and legal problems for the laboratory. Accordingly, many alternatives are being assessed, such as combustion gas analysis, but they have not replaced animal testing yet. With gas hazard testing, the exhaust gas temperature can be measured. The property of the initial reaction of a specific fire paint can be characterized by this temperature. The purpose of this study was to consider the improvement point for a gas hazard test through comparative analysis of the exhaust temperature and the time of death of the mice.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.6
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• pp.1-8
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• 2021

The performance of hidden camera cameras is improving day by day due to miniaturization and advanced technology integration according to the speed of technological development of smartphones. As this external networking computing environment is advanced and diversified, exposure to hidden cameras in addition to general safety cameras is also increasing. On the other hand, the technology for detecting and preventing hidden cameras is not keeping up with the development and speed of these hidden cameras. Therefore, in this study, the heat of the hidden camera was detected using infrared thermal detection technology based on general image and thermal image synthesis technology, and the reflectance of each wavelength according to the difference in ambient temperature was analyzed to reduce the false positive rate.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.621-626
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• 2012

In this study, the composite coating materials with improved thermal insulation property were prepared by incorporating the hollow micro-spheres with high heat transfer resistance. The UV curable resin system consisting of hexa aliphatic urethane acrylate (UP118), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), and photoinitiator (Irgacure184) was employed as an organic binder. The glass substrates were coated by the prepared composites via bar coating method and cured under UV radiation. The optical transparency, thermal insulation property, adhesion, and surface hardness of the glass coated with composites containing different type of micro-spheres were investigated. The incorporation of micro-spheres with only 20 vol% of content resulted in remarkable improvement in the thermal insulation property of the coated glass. In addition, the transparent coated glass with light transmittance of about 80% could be obtained when silica micro-sphere (SP) was used as a thermal barrier.

• Journal of Environmental Science International
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• v.25 no.2
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• pp.311-322
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• 2016

This study reduced and built Street Canyons created by skyscrapers in order to verify effect of Street Canyons by green wall within the city centre and analysed influence factors on temperature reduction according to applicative types of green wall in the lab. Applicative types were divided into three types such as non- greening type(Case A), one-side greening type(Case B), both side greening type(Case C). The result of analysis of each types showed that average temperature of Case B and Case C is respectively $1.0^{\circ}C$ and $1.7^{\circ}C$ lower than Case A. The result of analysis of WBGT was that the highest temperature was given by Case A($40.2^{\circ}C$) and second one was from Case B($39.8^{\circ}C$) and third one was from ($39.1^{\circ}C$) and in UTCI Case A records the highest temperature of $34.7^{\circ}C$ and Case B provided the second highest temperature of $33.9^{\circ}C$ and Case B gave the lowest temperature of $32.7^{\circ}C$. In PMV the highest temperature of 2.65 was from Case B and second one of 2.61 was from Case A and third one of 2.54 was from Case C. Duncan analysis of each types based on solar radiation and thermal comfort generated that there was analytical significance between Case A and Case B and Case B in terms of each types of average temperature reduction. The significance of thermal comfort in WBGT, MRT, PMV showed non-significance but, In UTCI it was analysed that there was significance between Case C and Case A.