• International Journal of High-Rise Buildings
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• v.3 no.2
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• pp.155-165
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• 2014

This study measured and compared the variation of ventilation rate and fan energy consumption according to various control strategies after installing wireless sensor-based pilot ventilation system in order to verify the applicability of demand-controlled ventilation (DCV) strategy that was efficient ventilation control strategy for underground parking lot. The underground parking lot pilot ventilation system controlled the ventilation rate by directly or indirectly tracking the traffic load in real-time after sensing data, using vehicle detection sensors and carbon monoxide (CO) and carbon dioxide ($CO_2$) sensor. The ventilation system has operated for 9 hours per a day. It responded real-time data every 10 minutes, providing ventilation rate in conformance with the input traffic load or contaminant level at that time. A ventilation rate of pilot ventilation system can be controlled at 8 levels. The reason is that a ventilation unit consists of 8 high-speed nozzle jet fans. This study proposed vehicle detection sensor based demand-controlled ventilation (VDS-DCV) strategy that would accurately trace direct traffic load and CO sensor based demand-controlled ventilation (CO-DCV) strategy that would indirectly estimate traffic load through the concentration of contaminants. In order to apply DCV strategy based on real-time traffic load, the minimum required ventilation rate per a single vehicle was applied. It was derived through the design ventilation rate and total parking capacity in the underground parking lot. This is because current ventilation standard established per unit floor area or unit volume of the space made it difficult to apply DCV strategy according to the real-time variation of traffic load. According to the results in this study, two DCV strategies in the underground parking lot are considered to be a good alternative approach that satisfies both energy saving and healthy indoor environment in comparison with the conventional control strategies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.605-610
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• 2004

Solid propellants allow thrusters to be light-weight, com-pact and robust because they require neither tank nor valve, Moreover, the solid propellant will not leak, spill or slosh. Consequently, the solid propellant thruster is one of the potential candidates for the microthruster. On the other hand, the control of the solid propellant combustion is difficult, since the conventional solid propellant continues to bum until all the stored propellant is consumed. Although particular devices like thrust reverser were designed to control the combustion, these devices were rarely used in the practical rocket motors. These devices rise thruster weight as well as complicate the thruster operation. In this study, a solid propellant microthruster using laser sustained combustion was designed in order to develop a high-efficiency microthruster overcoming the previously-mentioned difficulty. This designed thruster has semiconductor lasers and non-self-combustible solid propellants in addition to the conventional solid propellant thruster. In this designed thruster, the semiconductor laser controls the combustion of the non-self-combustible solid propellant. In order to demonstrate that the solid propellant combustion is controllable with laser, some non-self-combustible solid propellants were irradiated with the laser at a back-pressure of about 1㎪. A 40-W class Neodymium Yttrium Aluminum Garnet (ND:YAG) laser was used as a tentative alternate to the semiconductor laser. This experiment has shown that the solid propellant combustion was controllable with 10- W class laser irradiation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.671-686
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• 2004

The shock-induced combustion ramjet (shcramjet) is a hypersonic airbreathing propulsion concept which over-comes the drawbacks of the long, massive combustors present in the scramjet by using a standing oblique detonation wave (a coupled shock-combustion front) as a means of nearly instantaneous heat addition. A novel shcramjet combustor design that makes use of wedge-shaped flameholders to avoid detonation wave-wall interactions is proposed and analyzed with computational fluid dynamics (CFD) simulations in this study. The laminar, two-dimensional Navier-Stokes equations coupled with a non-equilibrium hydrogen-air combustion model based on chemical kinetics are used to represent the physical system. The equations are solved with the WARP (window-allocatable resolver for propulsion) CFD code (see: Parent, B. and Sislian, J. P., “The Use of Domain Decomposition in Accelerating the Convergence of Quasihyperbolic Systems”, J. of Comp. Physics, Vol. 179, No. 1,2002, pages 140-169). The solver was validated with experimental results found in the literature. A series of steady-state numerical simulations was conducted using WARP and it was deter-mined by means of thrust potential calculations that this combustor design is a viable one for shcramjet propulsion: assuming a shcramjet flight Mach number of twelve at an altitude of 36,000 m, the geometrical dimensions used for the combustor give rise to an operational range for combustor inlet Mach numbers between six and eight. Different shcramjet flight Mach numbers would require different combustor dimensions and hence a variable geometry system in or-der to be viable.

• Journal of KIBIM
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• v.6 no.3
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• pp.1-14
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• 2016

The usage of Building Information Modelling (BIM) in building projects has enabled improvement in project planning, implementation and collaboration process amongst various stakeholders within architecture, engineering and construction (AEC) industry. However, variations exist in the current practices of BIM implementation and coordination process in the industry. These variations result in inconsistent degree of BIM use across the construction industry. This inconsistency gives rise to several managerial and technological challenges such as data interoperability issues and purposeful integration and exchange of information within the BIM components. In order to tackle the issue, it is essential to analyse the different BIM approaches employed by the industry practitioners. BIM guidelines serve as a critical link between the BIM model, and its subsequent execution. They therefore provide the best reflection of BIM application and processes. This research paper aims to address the variations existing in BIM practices across the construction industry. It includes an extensive study of 21 existing, publicly available BIM-based guidelines in order to establish an understanding of the present state of practice and deduce issues and concerns related to them. All guidelines analysed in this paper are first categorised based on authorship and the release date for efficient comparison. The points of similarity and difference between them are thereby realized and outlined. In addition, the transition of project implementation process from traditional methods to BIM technology is also explained. The existence of inconsistencies in the BIM guidelines reviewed in this paper reflects the need of a BIM 'Code Compliance Check'. The Code Compliance Check will serve as a regulatory project guideline that will further improve the potential of BIM by incorporating a consistent BIM modelling methodology for the entire construction industry.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.368-372
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• 2007

Recently, construction companies prefer to use large scale system forms to prepare for lacking of skilled workers, aging and the chances of application of pre-build&post-sale policy. In result of the effort and interest, the duration for framework of domestic high rise buildings has been accomplished to 3-4days per floor but for the apartment housing which form over 90% of the domestic construction industry, and especially the middle story RC apartments which is the main part, the duration for framework is only about 6-8days per level. This is only about 50% of the duration per level of RC residential buildings in North America. In previous researches elementary technology, which has potential of duration reduction, was proposed and this research suggest the applicability in construction sites and ways to improve it using elementary technology applied Mock-up Test. Furthermore, we analyze the productivity and T/C usage rate of the 6day-Cycle and suggest an improved model.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.48 no.10
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• pp.537-543
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• 1999

We fabricated a resistive superconducting fault current limiter (SFCL) of a meander type based on a YBCO film with the meander cross section of 5 $\times$ $10^{-6}$$cm^2$, and performed current limitation experiments. The film was coated quench current was 9.6 Apeak at 60 Hz, and the fast quench time was 0.63 msec. The resistance of the limiter continuously increased for three cycles dut to the temperature rise in the gold layer. The temperature of the current limiting element reached the room temperature in 11 msec, $150^{\circ}C$ in 54 msec after quench, and was saturated afterwards. For $45^{\circ}$and $90^{\circ}$faults the fast quench times were 0.56 msec and 0.26 msec, respectively. The quench time is believed to be reduced because the fault occurred when the current was either increasing or at the peak value. This limiter effectively limited the fault current to about 1/5 of the potential current with no SFCL right after the fault and to about 1/8.5 in three cycles. We confirmed that the gold layer effectively carried out the role of heat dissipation as the SFCL was quenched.

• Journal of Korean Society for Atmospheric Environment
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• v.32 no.2
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• pp.131-157
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• 2016

A smog chamber has been an effective tool to study air quality, particularly secondary organic aerosol (SOA), which is typically formed by atmospheric oxidation of volatile organic compounds (VOCs). In controlled environments, smog chamber studies have validated atmospheric oxidation by identifying, quantifying and monitoring products with state-of-art instruments (e.g., aerosol mass spectrometer, scanning mobility particle sizer) and provided chemical insights of SOA formation by elucidating reaction mechanisms. This paper reviews types of smog chambers and the current state of smog chamber studies that have accomplished to find pathways of SOA formation, focusing on gas-particle partitioning of semivolatile products of VOC oxidation, heterogeneous reactions on aerosol surface, and aqueous chemistry in aerosol waters (e.g., cloud/fog droplets and wet aerosols). For future chamber studies, then, this paper discusses potential formation pathways of fine particles that East Asia countries (e.g., Korea and China) currently suffer from due to massive formation that gives rise to fatal health problems.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.98-103
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• 2015

Liquefied petroleum gas can be charged up to 85% of cylinder volume by enforcement regulations of safety control and business of liquefied petroleum gas act. The charged mass by enforcement regulations is considered by liquid expansion of internal liquefied petroleum gas at $65^{\circ}C$. But the temperature of liquid would not be suspended under $65^{\circ}C$ in a cylinder or portable vessel at certain situation. In the thermodynamics view point, the cylinder can be exposed to high pressure by liquid expansion. Consequently, it can be possible to potential risk such as physical explosion. Hence, this paper will offer a method of estimated internal pressure by liquid expansion at critical state in the closed system. Also, the structural factor which is given rise to volume increasement of cylinder is offered by experiment. This paper is expected as crucial reference for a cylinder design of liquefied petroleum gas.

• The Korean Journal of Pain
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• v.21 no.2
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• pp.126-130
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• 2008

Background: Females generally have a lower pain and temporal summation threshold than men. However, the results of studies designed to evaluate gender differences in the thresholds of heat pain and the temporal summation have been inconsistent. Newly developed device, CHEPS (Contact Heat Evoked Potential Stimulation) model of PATHWAY, have superiority on its fast rise and return time in temperature. Therefore we investigated gender differences in heat pain and temporal summation threshold. Methods: Forty healthy volunteers (20 males and 20 females) were enrolled in this study. A thermode was applied to the volar side of each volunteer's left forearm and heat pain and the temporal summation threshold was then measured. The heat pain threshold was estimated using the staircase method by starting from $36^{\circ}C$ and then increasing the temperature in $0.5^{\circ}C$ increments. The temporal summation threshold was estimated by applying five successive stimulation of the same temperature starting at $2^{\circ}C$ lower than the heat pain threshold and then increasing the temperature in $0.5^{\circ}C$ increments. Results: The mean heat pain thresholds was found to be $41.63{\pm}1.63^{\circ}C$ for males and $41.60{\pm}1.84^{\circ}C$ for females and the temporal summation thresholds were found to be $40.83{\pm}1.64^{\circ}C$ for males and $40.77{\pm}1.93^{\circ}C$ for females. The differences between males and females were not statistically significant. Conclusions: The result of this study suggested that there are no gender differences in heat pain and temporal summation threshold.

• Journal of the Society of Disaster Information
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• v.5 no.1
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• pp.78-100
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• 2009

This study is to protect peoples' life, minimize the property damage by coping with threats quickly and take more preventive measures in advance against nuclear bomb, CBR, and potential explosive. For this, CBRNE(Chemical, Biological, Radiological, Nuclear, Explosive) program research was used. Thanks to advance in technology, terrorist groups and even individuals make or keep nuclear and CBR weapons. And also it's likely that disaster and threats from a toxic gas, acute pathogens, accidents in the nuclear power plants and a high explosive could be happened a lot. Recently more organized terrorist groups maintain random attacks for unspecified individuals and also it's highly likely that a large-scale terrorist attack by WMD and CBRNEwill be done. To take strict measures against CBRNE attacks by terrorists is on the rise as an urgent national task. Moreover biological weapons are relatively easy and inexpensive to obtain or produce and cause mass casualties with a small amount. For this reason, more than 25 countries have already possessed them. In the 21 st century, the international safety environment marks the age of complicated threats : transnational threats such as comprehensive security and terror, organized crime, drug smuggling, illegal trade of weapons of mass destruction, and environmental disruption along with traditional security threats. These cause military threats, terror threats, and CBRNE threats in our daily life to grow. Therefore it needs to come up with measures in such areas as research development, policy, training program. Major industrial nations on CBRNE like USA, Canada, Switzerland, and Israel have implemented various educational programs. These researches could be utilized as basic materials for drawing up plans for civil defense, emergency services and worldwide countermeasures against CBRNE.