• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.84-90
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• 1997

The turboshaft engine with the free power turbine has been used for various purposes, for instance electric power generator, emergency power source, helicopter powerplant and so on. Steady-state simulation program was developed and experimental tests was carried out for comparing with computer simulation results. The test unit was composed of 1-stage centrifugal compressor, the can type combustor chamber, 1-stage radial type compressor turbine, and radial type free power turbine, and its output power is obtained from 3-phase AC generator. Main component characteristics which was used for the steady state simulation program, were obtained from the manufacturer of the test unit, and modified from experimental results of test unit. In comparison between computer simulation and experimental test results even though the test unit has the operational limit, deviation of component performance characteristics in simulation were within 6％ range of experimental results.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.23-30
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• 2016

Powder samples of natural lawsonite (Ca-lawsonite, $CaAl_2Si_2O_7(OH)_2{\cdot}H_2O$) was studied structurally up to 8 GPa at room temperature using monochromatic synchrotron X-ray powder diffraction and a diamond anvil cell (DAC) with a methanol : ethanol : water (16 : 3 : 1 by volume) mixture solution as a penetrating pressure transmitting medium (PTM). Upon pressure increase, lawsonite does not show any apparent pressure induced expansion (PIE) or phase transition. Pressure-volume data were fitted to a second-order Birch-Murnaghan equation of state using a fixed pressure derivative of 4 leading to a bulk modulus ($B_0$) of 146(6) GPa. This compression is further characterized to be isotropic with calculated linear compressibilities of ${\beta}^a=0.0022GPa^{-1}$, ${\beta}^b=0.0024GPa^{-1}$, and ${\beta}^c=0.0020GPa^{-1}$.

• Journal of the Korea Concrete Institute
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• v.25 no.1
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• pp.19-28
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• 2013

The longitudinal axial strain in the plastic hinge region of reinforced concrete (RC) columns influences on the structural behavior of RC structures subjected to reversed cyclic loading. This strain decreases the effective compressive strength of concrete and increases the lateral displacements between stories by causing the elongation of member length. This paper investigated the effects of the axial force on the elongation of a RC member by using a sectional analysis of RC members. The analytical and experimental results indicated that the axial force decreased the axial strain in the plastic hinge region of RC columns. In this study, a model was proposed to predict the axial strain of RC columns. The proposed model considering the effects of axial force ratio consisted of three path types ; Path 1-loading region, Path 2-unloading region, and Path 3-reversing cyclic loading region. The axal strains predicted by the proposed model were compared with the test results of RC columns with various axial force ratios, and agreed reasonably with the observed longitudinal strains.

• Journal of KSNVE
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• v.10 no.1
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• pp.97-106
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• 2000

The dynamic behavior of crankshaft-bearing system in scroll compressor has been investigated using the combined methodologies of finite elements and transfer matrices. The finite element formulation is proposed including the field element for a shaft section and the point element at balancer weight locations, bearing locations, etc., whereas the conventional method is used with the elements. The Houbolt method is used to consider the time march for the integration of the system equations. The linear stiffness and damping coefficients are calculated for a finite cylindrical fluid-film bearing by solving the Reynolds equation, using finite difference method. The orbital response of crankshaft supported on the linear bearing model is obtained, considering balancer weights of motor rotor. And, the steady state displacement of crankshaft are compared with a variation in balancer weight. The loci of crankshaft at bearing locations are composed of the synchronous whirl component and the non-synchronous whirl component.

• Proceedings of the Korea Multimedia Society Conference
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• 2003.11a
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• pp.36-39
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• 2003

본 논문에서는 비디오 컨텐츠 내에 소유자와 구매자 정보를 함께 포함하는 핑거프린팅 정보를 삽입하여 불법으로 배포된 핑거프린팅 컨텐츠로부터 배포자가 누구인지를 추적할 수 있는 기법을 보인다. 특히, 문헌[1]에서 제시된 시간축 웨이블릿 변환을 이용하여 핑거프린팅 정보가 삽입될 영역을 분리해 주고, 역 변환을 통해 전 영역의 비디오 프레임에 정보가 삽입되게 된다. 이로 인해 핑거프린팅된 컨텐츠의 상이성을 이용한 기존의 여러 공모공격에도 강인함을 보이고 있다. 또한, 비디오 컨텐츠의 특성상 MPEG2의 압축에도 불법 배포자를 추적할 수 있는 강인함을 보인다.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.1
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• pp.104-110
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• 1997

To predict the effect of ring expansion and ring compression on residual stress relief of Al 7175 ring rot]s, 2-D axisymmetric thermal analysis and elastoplastic analysis were performed. The residual stress distributions along the thickness of T73, T7351 and T7352 treated rings were measured using three step sectioning method. The measured results were compared to numerical ones for quenched and stress relieved rings. After quenching, calculated hoop and axial residual stresses were similar to measured ones for T73 treated rings. The residual stresses of T7351 and T7352 treated rings were decreased remarkably compared to T73 treated rings. The effect of axial residual stress relief was superior to that of hoop one, and also ring compression to ring expansion. It was concluded that ring compression is advantageous over ring expansion in view of stress relief effect and practicality, and vice versa in view of dimensional control and press power.

• Journal of the Society of Naval Architects of Korea
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• v.32 no.1
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• pp.141-146
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• 1995

In this study the plastic buckling analysis of a simply supported plate under biaxial compression/tension loading is carried out considering the plastic compressibility. Plastic buckling of a biaxially loaded rectangular plate is governed by two kinds of mechanism, the tension strengthening and plastic weakening under which the optimal combination of tension and compression is obtained for the buckling strength. To consider the plastic compressibility, the Drucker-Prayer plastic potential is employed. General eigenvalue equations are derived for a rectangular plate within the framework of small strain plasticity and isotropic hardening.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.45-52
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• 2005

The object of this study was a cold-formed steel wall stud panel sheathed by gypsum boards. In the beam-analysis, the panel was treated as a simple beam with a uniform lateral loading. The deflections were calculated by considering the primary factors that reduced the stiffness of the panel. In the column-analysis, the panel was treated as a bearing wall with an axial load. By using an energy method, nominal axial strength could be evaluated by considering both flexural buckling and torsional-flexural buckling. All calculations were programmed and compared with the results of the experiment. In the beam-analysis, experimental deflections were close to theoretical deflections. In the column-analysis, the experimental values were also close to theoretical values in axial strength.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.6
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• pp.975-981
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• 1987

Employing a speical yield function for porous metals, a set of special constitutive equations is formulated to predict elastic-plastic responses of porous metals under triaxial compression. The proposed contitutive equations are compared with experimental data for porous tungsten under hydrostatic compression and uniaxial strain compression.

• Journal of the Korean Institute of Gas
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• v.3 no.1
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• pp.14-20
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• 1999

This study describes the results of Coefficient of Performance(COP) analysis by cycle simulation for two types of absorption-compression hybrid cycle using the Water/Lithium Bromide solution pair. These types are basic hybrid systems introducing a mechanical compression process into the refrigerant vapor phase of the single effect absorption cycle. In absorption-compression hybrid cycles, coefficient of performance is improved compared with absorption cycle. Hybrid cycle Type 2 is considered as a key technology to support energy utilization system, given its capability of utilizing waste heat to drive system with a high level of efficiency.