• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.17-21
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• 2003

This paper presents a CAD interface system that imports CAD model data and exports input information to a CAPP(Compute Aided Process Planning) system to generate a sequence for block assembly operations. In developing this system we use an open architecture CAD kernel, OpenCASCASE. The functions of the system developed are visualization of the product, definition of relations between parts, and generation of relation graph and input file for CAPP. The functions are demonstrated with a simple example.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1969-1973
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• 2007

The purpose of this study is to investigate the performance of a sea water heat source cascade heat pump system. R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of $10^{\circ}C$. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.5 no.1
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• pp.7-11
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• 2009

The purpose of this study is to investigate the performance of a water heat source cascade heat pump system R717(Ammonia) is used for a low-stage working fluid while R134a is for a high-stage. In order to gain a high temperature supply water in winter season, the system is designed to perform a cascade cycle. In this study, two experiments were carried out. One is a system starting test from the low load temperature of $10^{\circ}C$. The other is a system performance investigation over the R717 compressor capacity changes. Experimental results show that when it starts from the low load temperature, the suction temperature of the low-stage compressor is higher than that of a high-stage. The system performance increases when a water source temperature or a low-stage compressor rotational frequency goes higher.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1123-1128
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• 2009

In this paper, the cycle performance characteristics of a cascade refrigeration system with internal heat exchanger using natural refrigerants is presented to offer the basic design data for the operating parameters of the system. This system considered in this study is consisted of a high temperature cycle using a carbon dioxide(R744) and low temperature cycle using refrigerants such as R290, R1270, R600a and Ethane. The main results were summarized as follows : The COP of the cascade refrigeration system of R600a with internal heat exchanger is the highest grade in low temperature cycle using refrigerants such as R290, R1270, R600a and Ethane. The COP of the cascade refrigeration system with internal heat exchanger only in high temperature cycle is the highest value among three type cycle, such as only low temperature cycle, only high temperature cycle and all the cycle.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.2
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• pp.189-195
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• 2011

In this paper, prediction and comparison on COP(coefficient of performance) of R744-R404A cascade refrigeration system are presented to offer the basic design data for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, compressor efficiency, and condensing and evaporating temperature in the R404A high- and R744 low-temperature cycle, respectively. The main results were summarized as follows : The prediction for performance of R744-R404A cascade refrigeration system have been proposed through multiple regression analysis and compared with other researcher's correlations. As a result, prediction proposed in the study shows disagreement with existing equations. Therefore, it is necessary to propose the more accurate correlation predicting the COP of R744-R404A cascade refrigeration system through an addition experiments.

• BMB Reports
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• v.43 no.2
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• pp.103-109
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• 2010

Modification of proteins by the reversible covalent addition of the small ubiquitin like modifier (SUMO) protein has important consequences affecting target protein stability, sub-cellular localization, and protein-protein interactions. SUMOylation involves a cascade of enzymatic reactions, which resembles the process of ubiquitination. In this study, we characterized the SUMOylation system from an important crop plant, rice, and show that it responds to cold, salt and ABA stress conditions on a protein level via the accumulation of SUMOylated proteins. We also characterized the transcriptional regulation of individual SUMOylation cascade components during stress and development. During stress conditions, majority of the SUMO cascade components are transcriptionally down regulated. SUMO conjugate proteins and SUMO cascade component transcripts accumulated differentially in various tissues during plant development with highest levels in reproductive tissues. Taken together, these data suggest a role for SUMOylation in rice development and stress responses.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.131-135
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• 2003

WDM(Wavelength division multiplexing) light wave communication system requires MUX/DeMUX and optical filter OADM can be used to extract and add the specific wavelength channel from the transmission line. In this paper, we propose the OADM based on MZI and cascade FBG. It is able to minimize system and reduce sidelobe. So, we have considered MZI structure and 3dB coupler. Using the coupled mode theory. We also analyze out characteristics of OADM and experiment. From results obtained by experiment and computer. Simulation, the proposed OADM with cascade FBG works well. we hope that the obtained result in this paper con be used as the data to design the OADM with cascade FBG.

• Journal of the Korean Society of Propulsion Engineers
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• v.8 no.4
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• pp.1-8
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• 2004

In this paper, a small supersonic wind tunnel is designed and built to study the flow characteristics of a supersonic impulse turbine cascade. The flow is visualized by means of a sin91e pass Schlieren system. The supersonic cascade with 3-dimensional supersonic nozzle was tested over a wide range of nozzle installation angle. Highly complicated flow patterns including shocks, nozzle-cascade interaction and shock boundary layer interactions are observed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.4
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• pp.464-471
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• 1999

This paper describes a design of the helium-recondensing system utilizing cascade Roebuck refrigerators. Superconducting generator or motor has the superconducting field winding in its rotor that should be continuously cooled by cryogen. Since liquid helium transfer from the stationary system to the rotor is problematic, cumbersome, and inefficient, the novel concept of a rotating helium-recondensing system is contrived. The vaporized cold helium inside the rotor is isothermally compressed by centrifugal force and expanded sequentially in cascade refrigerators until the helium is recondensed at 4.2K. There is no helium coupling between the rotor and the stationary liquid helium storage. Thermodynamic analysis of the cascade refrigeration system is performed to determine the key design parameters. The loss mechanisms are also explained to identify entropy generation that degrades the performance of the system.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
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• v.11 no.1
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• pp.15-20
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• 2015

In this study, the optimization and performance characteristics of a cascade heat pump system was analyzed with the variation of low stage refrigerant charge amount. The cascade heat pump was designed and constructed with R134a and R410A as the refrigerant for high stage and low stage cycle, respectively. Experiments were conducted by varying the low stage charge amount and the performance characteristics of the cascade heat pump were studied. The refrigerant charge amount of the low stage cycle was varied between the ranges of -15% and +10% of the optimum charge amount. The performance variation experienced in the cascade heat pump due to the variation of refrigerant charge amount shows greater effect in the undercharge regions than the overcharge regions. COP reduction in the undercharge region is larger than the decrease in the overcharge region. Some cycle variation such as power consumption and cycle pressure according to low stage refrigerant charge amount showed different trends comparing with those according to high stage refrrgerant charge amount. Therefore, the optimum charge amount of the cascade heat pump should be determined based on the experimental data obtained by the variation of high and low stage refrigerant charge amount.