• Aerospace Engineering and Technology
• /
• v.5 no.2
• /
• pp.159-165
• /
• 2006

In this study, structural analysis is executed about cone structure of KSL V-1 2nd stage KMS(kick motor support structure) which is designed for support the load developed from 2nd stage kick motor. KMS is consisted of cone structure and truss structure which is designed for supporting load developed from 2nd stage payload. Applied loads to cone structure are tension load by inertia developed from kick motor and compression load developed from kick motor. Also, shear and bending load are developed according to flight condition. In this study, structural analysis of cone structure is executed under several load condition which may be applied to cone structure. Also, structural analysis with two finite element model is performed according to pressure vent scheme. In result of structural analysis, critical load condition is equivalent tension load with cut-out.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.06a
• /
• pp.705-708
• /
• 2009

For the Gas hydrate Research and Development in Korea, the prospect area I & II was surveyed and drilled during the first phase. At the result, we succeeded to discovering gas hydrate real sample at BSR reflection and vent structure. This expedition processing contributes to developing the offshore seismic survey technologies and data processing of Korea. But Korean gas hydrate test production research, in spite of activating test production at other countries, is such a limitation about technician, GH production technologies and E&P processing. First of all, there is no exist in Korea to application site for the their production research results. In this paper, we have studied the gas hydrate reservoir selection technics of the DOE & BPXA for the ANS test production. And this result will helpful to preparation of gas hydrate test production in Korea.

• Proceedings of the Korean Society For Composite Materials Conference
• /
• 2002.10a
• /
• pp.280-283
• /
• 2002

In the manufacturing of large scale composite structures, the cost-effective processing and the enhancement of structural performance are critical. One of the most effective ways for this purpose is to use stitched multiaxial warp knitted (MWK) perform in the resin transfer molding process. This study reports the effect of stitching on the mechanical properties of MWK composites, and the feasibility processing of the thick U-beam structure utilizing the stitched preforms. Permeability of the preform, viscosity and cure property of the epoxy resin have been measured. The results of resin flow analysis has been used in determining the gate/vent locations of the RTM mold. Cross-sectional observation of the channel beam prototype demonstrated that the resin impregnation was almost complete, except for some surrounding area of stitched yarns.

• Proceedings of the KIEE Conference
• /
• 1987.11a
• /
• pp.439-443
• /
• 1987

This paper presents a method for constructing model of manufacturing processes for simulation and design of the discrete control logic. The models represent the discrete vent evolution of the system as well as features of the underlying continues processes, for applications such as discrete parts manufacture and assembly, the process is decomposed into operations and for each operation the required resources and associated discrete resource slates are Identified. The structure of the discrete-level control is modeled by modified Perti nets which are synthesized from single resource activity cycles. Construction of nets provides discrete control logic with guaranteed properties based on extended Petri nets theory, for illustration, the proposed method is applied to the high-level discrete control of a two-robotic assembly cell.

• Journal of the Korean Institute of Rural Architecture
• /
• v.23 no.4
• /
• pp.63-71
• /
• 2021

The purpose of this study was to investigate whether the standard models for rural housing and wooden housing model have performance for hygrothermal and to propose a way of improvement relevant to hygrothermal performance for those models. All of the models to be analyzed were found to have some parts that were absent of stability in terms of performance for hygrothermal. In the process of analyzing the causes and proposing improvement measures, the following conclusions were derived. Fist, The exterior surface of the structure should be composed of a structure with good moisture permeability, and for the interior surface, a variable vapor retarder paper should be applied in consideration of the reverse condensation phenomenon in summer. Second, in terms of performance for hygrothermal, applications of external insulation plaster finish to the exterior wall or of ventilation method using a rafter vent on the roof should be avoided. Third, a rain screen method with a ventilation layer should be applied to the exterior wall, and a method of constructing ventilation layer separated from the insulation layer with a vapor retarder paper should be applied to the roof. Fourth, the application of insulation materials having capillary action, such as wood fiber insulation board or cellulose insulation board, contributes to more stable performance for hygrothermal.

• Animal cells and systems
• /
• v.14 no.4
• /
• pp.315-322
• /
• 2010

We studied and compared the age structure, body size, and growth rates of field populations of two Korean salamander species (Hynobius yangi and Hynobius quelpaertensis) to elucidate important aspects of basic population dynamics of these two endemic Hynobius species. In both populations, females were sexually mature at three years of age, while H. yangi and H. quelpaertensis males matured at two and three years of age, respectively. Both males and females of H. yangi and H. quelpaertensis attained a maximum age of 11 years and 10 years, respectively. In both species, the snout-vent length (SVL) and body weight (BW) of the females were greater than those of the males. The SVL, BW, and asymptotic SVL of both male and female H. yangi were smaller than those of H. quelpaertensis. The adult growth rates after sexual maturation of male and female H. yangi were lower than those of H. quelpaertensis, possibly resulting in the smaller body size of the former, although overall growth coefficients were not significantly different between the two species. We also compared the age structure and growth rates of three Korean and three Japanese species of Hynobius.

• Journal of Ecology and Environment
• /
• v.31 no.1
• /
• pp.31-36
• /
• 2008

Larvae of the long-tailed clawed salamander, Onychodactylus fischeri, have a relatively long larval period, spending a year or more within the stream where they hatch; therefore, a well-established larval population could be critical for the conservation of adult populations. To study the population dynamics of long-tailed clawed salamander larvae, we surveyed a field population once or twice a month from September, 2005 to June, 2006, and determined the age of larval clawed salamanders collected from three different populations in October, 2004 using skeletochronology. The age of long-tailed clawed salamander larvae ranged from 0 to 3 years. New recruitment of larvae in the population primarily occurred in November, 2005, and mid-March, 2006. Larvae with a snout-vent length of more than 30 mm disappeared from the streams in September, 2005, suggesting that two to three year-old clawed salamander larvae metamorphosed during this period.

• Applied Science and Convergence Technology
• /
• v.26 no.5
• /
• pp.139-142
• /
• 2017

In this paper, InP-based InGaAs/InAlAs quantum cascade lasers(QCLs) providing nearly zero emission wavelength mismatch between the measured emission wavelength and the designed transition wavelength of QCLs is presented. The zero emission wavelength mismatch of QCLs influenced by both the accurate compositions and thicknesses of the low-pressure metal-organic vapor-phase epitaxy(MOVPE) grown InGaAs and InAlAs layers throughout the core and the abrupt composition transitions between InGaAs and InAlAs layers. The abrupt interfaces between InGaAs and InAlAs layers have been achieved throughout the core structure by means of controlling individually purged vent/run valves of a closed coupled showerhead reactor. In addition, maintaining substrate temperature constant during InGaAs/InAlAs core growth was a partial factor of uniformity improvement of QCLs. These approaches for reducing the possible discrepancies between the designed and MOVPE grown epitaxial structures could lead to improvement of QCL performance.

• Agricultural and Biosystems Engineering
• /
• v.1 no.2
• /
• pp.73-80
• /
• 2000

Aerodynamics in a naturally ventilated multi-span greenhouse with plants was analyzed numerically by the computational fluid dynamics (CFD) simulation. To investigate the potential application of CFD techniques to greenhouse design and analysis, the numerical results of the CFD model were compared with the results of a steady-state mass and energy balance numerical model. Assuming the results of the mass and energy balance model as the standard, reasonably good agreement was obtained between the natural ventilation rates computed by the CFD numerical model and the mass and energy balance model. The steady-state CFD model during a sunny day showed negative errors as high as 15% in the morning and comparable positive errors in the afternoon. Such errors assumed to be due to heat storage in the floor, benches, and greenhouse structure. For a west wind of 2.5 m s$^{-1}$ , the internal nonporous shading screens that opened to the east were predicted to have a 15.6% better air exchange rate than opened to the west. It was generally predicted that the presence of nonporous internal shading screens significantly reduced natural ventilation if the horizontal opening of the screen for each span was smaller that the effective roof vent opening.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.28 no.7
• /
• pp.780-788
• /
• 2004

This paper reports the fluid flow and heat transfer around a module cooled by forced air flow generated by a piezoelectric(PZT) cooling fan. The fluids are locally accelerated by a flexible PZT fan which deflects inside a fluid transport system of comparatively simple structure mounted on a PCB in a parallel-plate channel(450${\times}$80${\times}$700㎣). Input voltages of 20-100V and a resonance frequency of 23㎐ were used to vibrate the cooling fan. Input power to the module was 4W. The fluid flow around the module was visualized by using PIV system. The temperature distributions around a heated module were visualized by using liquid crystal film(LCF). The cooling effect using a PZT fan was independent of the vent area ratios at the channel inlet and was similar to the forced convection cooling. We found that the flow type was Y-shape and the cooling effect was increased by the wake generated by a piezoelectric cooling fan.