• 대한수학회논문집
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• 제33권1호
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• pp.13-36
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• 2018

In this paper, we obtain some formulae for harmonic sums, alternating harmonic sums and Stirling number sums by using the method of integral representations of series. As applications of these formulae, we give explicit formula of several quadratic and cubic Euler sums through zeta values and linear sums. Furthermore, some relationships between harmonic numbers and Stirling numbers of the first kind are established.

• Journal of applied mathematics & informatics
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• 제41권2호
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• pp.331-343
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• 2023

In this paper, we give explicit identities for the degenerate q-poly-tangent numbers and polynomials. Finally, we obtain the relation of degenerate q-poly-tangent polynomials and Stirling numbers of the first kind and Stirling numbers of the second kind.

• 한국초전도ㆍ저온공학회논문지
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• 제19권4호
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• pp.12-17
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• 2017

Design of Reverse Stirling Cycle based refrigerator can be predicted by Schmidt theory as a useful tool and by experiment it is found that for practical purposes the power and efficiency predicted by this analysis are about 35% of the actual values. Therefore, appropriate provision is to be made for getting the realistic result with the minimum deviation. The present paper first investigates the suitability of application of Schmidt design analysis for standard ZIF-1002 and PLN-106 Single cylinder Cryogenerator model. As the result is found to be optimistic, the same design procedure is applied for the design of a separate Cryogenerator for generating a cooling effect which is sufficient to produce 7 kg per hour liquid nitrogen using an indigenous condenser of 80% effectiveness. The paper describes all the details of the design methodologies and relevant results are found to be satisfactory.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.67-70
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• 2002

The Stirling cryocooler with helium refrigerant has been widely used for the cooling of the infrared detector, and the alternatives of the helium in the Stirling cryocooler are nitrogen and hydrogen gas. In this study, the performance experiment of the small FPFD(Free Piston and Free Piston) type Stirling cooler and the moving coil type, dual acting linear compressor was performed when the nitrogen and helium is used for the working fluid The results show that the nitrogen refrigerant has small cooling capacity compared with the helium, but the performance characteristics of the linear compressor does not greatly changed.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2002년도 학술대회 논문집
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• pp.63-66
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• 2002

A free piston and free displacer (FPFD) Stilting cryocooler for the cooling infrared and cryo-sensor is currently under development at Korea Institute of Machinery & Materials. In this study, the dynamic characteristics of the displacer in the expansion space of the Stirling cooler was investigated by experiment. The experimental results show that the Stirling cryocooler has maximum cooling capacity at the certain relation between operating frequency and natural frequency of the displacer and the operating frequency of the Stirling crycooler should be determined by natural frequency of the linear compressor and displacer.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.157-160
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• 2006

The Dish/Stirling system with the Stirling engine is currently used to convert solar energy directly to electrical energy successful operation of dish/Stirling system is supported by hybrid system, which will allow continuous operation driven by solar and combustion heat ins. The hybrid Receiver has to be provided with an additional combustion system. The heat pipe receiver and conbustion system were manufactured and tested for thermal characteristics of receiver. Maximum temperature difference along the heat pipe surface is $200^{\circ}C$. Emission measurements showed low NOx values of 28 to 46 ppm and very high CO values of 18 to 201 ppm.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.731-734
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• 2001

A cryogenic stirling cooler is currently under development at Korea Institute of Industrial Technology(KITECH). Cryocooler has many kinds of types. The stirling cooler is the most appropriate one for under 80K with the trait of long life cycle and small size. The stirling cooler uses helium as a working fluid. Helium is pressurized by the linear compressor which is driver by linear motor. In this paper, the change of pressure and volume is studied by the isothermal analysis method. It is necessary to investigate the optimized pressure to meets the highest COP. The compressor's piston and expender's displacer interact according to the working fluid's pressure level and the phase difference. This paper presents the relation between the initial pressure and the work of cryocooler. By that results, we can predict the performance of linear compressor.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 2001년도 학술대회 논문집
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• pp.159-162
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• 2001

A Stirling cryocooler is relatively compact, reliable, commercially available, and uses helium as a working fluid. The FPFD stirling cryocooler consists of two compressor pistons driven by linear motors which makes pressure waves and a pneumatically driven displacer piston with regenerator. It is the most suitable design for a mechanical cryocooler utilized in night vision environment. In order to get optimum operating frequency, natural frequency of piston and displacer, optimum phase angle between piston and displacer, cooling capacity, performance tests of the Stirling cryocooler by the frequency characteristics were performed.

• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.62-68
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• 2001

This paper presents manufacturing process and test results in the optimum pressure and operating frequency for the free piston free displacer(FPFD) Stirling cryocooler designed and manufactured by Korea Institute of Machinery &Materials (KIMM). FPFD Stirling cryocooler is currently under development uses opposed linear motors to drive opposed pistons . The performance of FPFD Stirling cryocooler is evaluated as a function fo charging pressure and operating frequency. In general as the operating frequency of the compressor is increaed but natural frequency of the displacer is almost constant. The prototype has achieved no load temperature of 49K and cooling capacity of 0.5W at 7.2K.

• 대한기계학회논문집B
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• 제20권4호
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• pp.1426-1436
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• 1996

The effectiveness of the regenerator pertaining to Stirling cycle machines is studied by analyzing the heat transfer characteristics of the oscillating flow in a tube, and a new consistent definition of the regenerator effectiveness can be expressed by the ratio of the heat transfer in axial direction (Q$\_$axial/) to that in transverse direction (Q/su w/), and its approximate form is obtained as a function of Nusselt number for practical utility. Since an approximate value of the ratio Q$\_$axial//Qsub w/ can be expressed in terms of the time-averaged rather than transient temperatures, this expression is useful to estimate the heat transfer coefficient in the Stirling machine regenerator experimentally.