• Journal of the Korean Society for Railway
• /
• v.10 no.1 s.38
• /
• pp.67-73
• /
• 2007

Experiments were carried out to investigate smoke movement in platform of a subway station which currently is in service in Pusan, the second largest city in Korea. The recently constructed underground station of the "bank type" (two platforms on both sides of track) which is the popular layout of platforms in Korea, is chosen in Pusan. The smoke generator and heater are used for simulating the smoke movement at the fire break in the platform located in the 2nd basement of the station. Video recordings were used to monitor smoke lowering. In this study, the movements of smoke in the underground station are investigated under various smoke-control operating modes. Three tests wire conducted according to its operating mode of the ventilation systems in the platform: no operation of any ventilation systems, smoke extraction mode in occurrence of fire (presently running mode) and full capacity of smoke extraction where all vents are activated in the platform. The results can be used for comparing with the numerical prediction results of fire subway stations.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.3
• /
• pp.84-91
• /
• 2001

Comparison between performance of a plate fin and that of a modified plate fin is investigated as a function of the position, the non-dimensional width and height of wings as well as the non-dimensional fin length using a two-dimensional separation of variables method. The ratio of the incremental rate of heat loss to that of the area of a modified plate fin is also presented as a function of the height of wings. The modified plate fin is made by attaching the wings to upper and lower sides of a plate fin. One of the results shows that performance of a modified plate fin is more improved as the wings approach left (higher) thermal reservoir.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2006.11a
• /
• pp.197-200
• /
• 2006

The bond characteristics of three different types of glass fiber reinforced polymer(GFRP) reinforcing bars with different surface deformations were studied experimentally. Each specimen consisted of a concrete prism, 150 by 150 mm on each edge, with the longer axis in the vertical direction. Two rebars were embedded in each specimen, perpendicular to the longer axis and parallel to and equidistant from the sides of the prism. In vertical direction, one rebar was located at 75 mm from the bottom of the prism, and the other 225 mm from the bottom. All testing procedures including specimens preparation, set-up of test equipments and measuring devices were made according to the recommendations of CSA Standard S806-02.It was found that the bottom reinforcements showed higher bond stress than that of the top rebars.

• 유체기계공업학회:학술대회논문집
• /
• 2003.12a
• /
• pp.697-703
• /
• 2003

For a single stage two cylinder rotary compressor, an analytical study has been made on the discharge gas pulsation. Discharge system of the twin rotary compressor consists of lower and upper mufflers and connecting passage holes between them, and cavities on both sides of the motor and passages between them. Acoustic modeling for the discharge system by transfer matrix method gives acoustic impedances at discharge valves so that gas pulsation at the valve sections can be obtained from discharge mass velocity. Since the mass velocity and the pressure pulsation at the valves are affected by each other, iteration should be made for convergence. Gas pulsations at other sections can also be calculated by using transfer matrix.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.4C no.3
• /
• pp.117-122
• /
• 2004

In order to help understand the growth mechanisms of demetallization due to self healing on a metallized polypropylene film (MPPF), several types of defects affecting the breakdown of capacitor dielectrics were made. The breakdown voltages with dielectric thickness were measured at self healing and the demetallized area was evaluated for all of the self healing events. The shapes and growth processes of the demetallized spots on the dielectrics were investigated. As a result, self healing mainly occurred at pin tips, wrinkle sides, and junctions of the wrinkles, and the breakdown voltages strongly depended on the thickness of the dielectrics. In addition, the demetallized area due to self healing was governed by the breakdown voltage and it has been mainly grown by some factors; the applied voltage; the consequent self healing events taking place at the circumference of the original self healing spots; the conductive paths formed by two or more self healing spots and by the consequent self healing spots.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.4 no.1
• /
• pp.31-36
• /
• 2005

In this paper, a planar type bandpass filter in multilayered PCB is presented. The multilayered PCB structure has some advantages on fabricating microwave devices such as the size reduction and ability of tight coupling by folding or embedding. The proposed BPF has two transmission zeros at the both sides of the center frequency by using independent electric and magnetic coupling structure. The designed BPF with four layer teflon PCBs of dielectric constant 2.94 has dimensions of 24x20x1.524 in mm, center frequency of 2.47GHz and bandwidth of about l00MHz. A good agrement is achieved between the measured result and the simulated one. The influences of air gaps between the layers are also analyzed and presented.

• Proceedings of the KSRS Conference
• /
• 2003.11a
• /
• pp.132-134
• /
• 2003

The likelihood ratio, logistic regression and artificial neural networks methods are applied and verified for analysis of landslide susceptibility in Yongin, Korea using GIS. From a spatial database containing such data as landslide location, topography, soil, forest, geology and land use, the 14 landsliderelated factors were calculated or extracted. Using these factors, landslide susceptibility indexes were calculated by likelihood ratio, logistic regression and artificial neural network methods. Before the calculation, the study area was divided into two sides (west and east) of equal area, for verification of the methods. Thus, the west side was used to assess the landslide susceptibility, and the east side was used to verify the derived susceptibility. The results of the landslide susceptibility analysis were verified using success and prediction rates. The v erification results showed satisfactory agreement between the susceptibility map and the exis ting data on landslide locations.

• Nuclear Engineering and Technology
• /
• v.52 no.1
• /
• pp.51-58
• /
• 2020

Despite the recent growth of interest in molten salt reactor technology and the crucial role which heat transfer plays in the design of power reactors, specific studies on the design of heat exchangers for the Molten Salt Fast Reactor have not yet been performed. In this work we deliver a preliminary but quantitative analysis of the intermediate heat exchangers, based on reference design data from the SAMOFAR H2020-Euratom project. Two different promising reference technologies are selected for study thanks to their compactness features, the Printed Circuit and the Helical Coil heat exchangers. We present preliminary design results for each technology, based on simplified design tools. Results highlight the limiting effects of the compactness constraints imposed on the fuel salt inventory and the allowed size. Large pressure drops on both flow sides are to be expected, with negative consequences on pumping power and natural circulation capabilities. The small size required for the flow channels also represents possible fabrication issues and safety concerns regarding channel blockage.

• Journal of the Korean Society for Precision Engineering
• /
• v.21 no.11
• /
• pp.83-90
• /
• 2004

In this paper we present a new real-time visual servoing unit for laparoscopic surgery This unit can automatically control laparoscope manipulator through visual tracking of laparoscopic surgical tool. For the tracking, we present two-stage adaptive CONDENSATION(conditional density propagation) algorithm to extract the accurate position of the surgical tool tip from a surgical image sequence in real-time. This algorithm can be adaptable to abrupt change of laparoscope illumination. For the control, we present virtual damper system to control a laparoscope manipulator safely and stably. This system causes the laparoscope to move under constraint of the virtual dampers which are linked to the four sides of image. The visual servoing unit operates the manipulator in real-time with locating the surgical tool in the center of image. The experimental results show that the proposed visual tracking algorithm is highly robust and the controlled manipulator can present stable view with safe.

• Journal of Plant Biology
• /
• v.27 no.2
• /
• pp.95-103
• /
• 1984

The Populus maximowiczii dominated forest of the Sangcheon ravine, Mt. Seolag, is distributed in the area with the conglemerates substrate, along the ravine stream from 170m to 550m in altitude. Toward the both slopes of the northern and southern peak from the stream side, the zonal distribution of vegetation was recognized; P. maximowiczii forest of Pinus densiflora forest and deciduous broad leaved forest. The pure community of P. maximowiczii with even more 80-98% in relative basal area (aspen basal area/basal area) was found in the ravine area from 360m to 420m in altitude, the optimal ranges in the species and community by two dimensional ordination with thermal and xeric cline axis. The species compete with Pinus densiflora, in the ravine stream side, and with deciduous broad leaved tree species such as Fraxinus rhynchophylla, Prunus sargentii, Lindera obtusiloba, in the mountain slope sides. On the other hand, the ravine vegetation, including the aspen forest, was classified into Pinus densiflora, Pinus densiflora-Carpinus laxiflora, Pinus densiflora-Populus maximowiczii, jessoensis, Acer mono-Fraxinus rhynchophylla, Carpinus laxiflora-Quercus mongolica, Quercus variabilis-Quercus ariena, Quercus ariena, Quercus variabilis-Stephanandra incisa, Picrasma quassioides-Celtis sinensis, Betula davurica-Zanthoxylum schinifolium and Styrax obassia-Lindera obtusiloba association.