• Journal of Astronomy and Space Sciences
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• v.23 no.2
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• pp.153-160
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• 2006

A Protomodel Space Infrared Cryogenic System (PSICS) cooled by a stirling cry-ocooler has been designed. The PSICS has an IR sensor inside the cold box which is cooled by a stirling cryocooler with refrigeration capacity of 500mW at 80K in a vacuum vessel. It is important to minimize the heat load so that the background thermal noise can be reduced. In order to design the cryogenic system with low heat load and to reduce the remained heat load, we have performed numerical analyses. In this paper, we present the design factors and the results obtained by the thermal analysis of the PSICS.

• Review of KIISC
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• v.2 no.4
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• pp.37-47
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• 1992

이 논문에서 우리는 여러 가지 분할 항등식을 유도했고 제한된 분할에 관한 새로운 항등식을 증명하고, 분할의 기본적인 이론과 분할함수(Partition Number Function)가 다항식 함수가 아니라는 것을 보이며, n의 분할의 수 p(n)에 대한 ㅎ계(Lower Bound)를 얻기 위해 Stirling의 n !에 대한 근사값을 소개한다. 그리고Hardy-Ramanujan 공식, Euler 항등식과 p(n)의 순환식을 유도하며, 그리고 d$_{m}$ (n)이 n을 m개의 부분으로 분할하는 분할의 수를 나타낼 때 우리는 d$_{m}$ (n) 에 관한 일반적인 공식을 p(n)과 함께 행렬식의 형태로 표현한다.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.108-113
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• 2004

This paper presents methods to improve performance of the power supply system in a NASA deep space explorer. In the Stirling engine driven reciprocating Brushless DC (BLDC) generator, the accurate position information of the prime mover is important to diagnose the performance of the engine and prevent distortion of the output power. Since sensors to detect the position are fragile and unreliable, and conventional sensorless techniques have drawbacks in the low speed region, a novel sensorless position detection technique for the prime mover has been proposed and verified. Another major issue of the generator for the spacecraft is power density maximization. The mass of the power system is important to the mass of the satellite. Therefore, the components of the spacecraft should be lightweight. Conventional rectification methods cannot achieve the maximum power possible due to non-optimal current waveforms. The optimal current waveform for maximizing power density and minimizing machine size and weight in a nonsinusoidal power supply system has been derived, incorporated in a control system, and verified by simulation work.

• Progress in Superconductivity and Cryogenics
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• v.7 no.3
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• pp.43-46
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• 2005

A Protomodel Space Infrared Cryogenic System (PSICS) cooled by a stirling cryocooler was designed. The PSICS has an IR sensor inside a cold box which is cooled by a stilting cryocooler with refrigeration capacity of 500mw at 80K in a vacuum vessel. It is important to minimize heat load for reducing background thermal noise. In order to design the cryogenic system of low heat load and to reduce heat load, we did several numerical analyses and tested using boil-off calorimetry with liquid nitrogen to measure the heat leak of the system. In this paper, we present the results obtained by thermal analysis and heat load measurement for designing the PSICS.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.358-361
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• 2002

The millirneterwave high-T$_{c}$ superconducting(HTS) down-converter sub-system with the HTS/III-V integrated mixer as the central device is demonstrated first. The constituent components of HTS down-converter sub-system such as a single balanced type integrated mixer with rat-race coupler, a cavity type bandpass filter (26 GHz), and a HTS planar lowpass filter(1 GHz), semiconductor LNA and IF-power amplifier, a driving electronic module for A/D converter, and a Stirling type mini-cooler module were combined into an International stand- and rack of 19-inch. From the RF(-61 dBm, 26.5GHz)and LO signal(-1 dBm, 25.6 GHz), IF signal(0dBm, 0.9 GHz) agreed with simulated results is obtained.d.

• Progress in Superconductivity and Cryogenics
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• v.17 no.3
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• pp.57-61
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• 2015

A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.

• Design & Manufacturing
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• v.13 no.1
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• pp.19-24
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• 2019

Currently, the world is paying keen attention to the production of renewable energy along with environmental issues, and the share of renewable energy in the world is rising above that of nuclear power. Especially when Korea, which is heavily dependent on foreign countries, needs to reconsider its national competitiveness due to the recent high oil prices, the government's energy policy is to develop and use renewable energy that replaces fossil fuels. In particular, solar energy, the most actively studied and commercialized field of renewable energy, is the main research for solar energy and is commercialized and used. However, the efficiency of solar energy has already reached saturation. Studies are also focusing on increasing the reflectivity of solar energy to increase efficiency. Therefore, this paper proposes a solar collection system that can utilize solar energy rather than solar energy. The proposed solar heat collection system uses solar tracking systems to effectively collect solar energy, particularly those that can be easily produced using single-modular reflectors and have price competitiveness. In addition, temperature measurement experiments with temperature measuring sensors were conducted to ensure reliability in order to verify the results interpreted.

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.1-17
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• 1994

잠수함추진방식은 크게 원자력 추진과 재래식 추진으로 나눌수 있다. 최근에는 재래식 추진방식과 하이브리드 개념으로 운용될 수 있는 AIP(Air Independent Propulsion)방식도 활발히 연구되고 있다. AIP추진으로는 폐회로 디젤기관추진(Closed Cycle Diesel Engine Propulsion), 연료전지추진(Fuel Cell Propulsion), 스터링기관추진(Stirling Engine Propulsion) 및 폐회로터빈추진(Closed Cycle Turbin Propulsion) 등이 있다. 이러한 잠수함 추진체계에 대해 앞으로 크게 세부분으로 나누어 그 현황과 발전추세를 살펴보고자 한다. 즉, 초기의 순수전기추진방식으로 불리는 재래식 추진체계, 재래식 추진방식의 한계를 극복하기 위해 최근 활발히 연구되고 있는 외기와 무관한 추진장치인 폐회로 추진체계, 그리고 궁극적으로는 에너지의 문제로 귀착되어 거의 무한대의 에너지원을 가지고 있는 원자력 추진체계로 구분하여 그 현황과 발전내용을 살펴 봄으로써 잠수함추진체계의 국내연구 개발방향정립에 조금이나마 보탬이 되었으면 합니다. 또한 차세대 추진장치로 불리는 전자유체 추진방식에 대해서는 한국박용기관 학회지 1993년 4월호 "박용전자유체(MHD) 추진장치"를 참조하시기 바랍니다.조하시기 바랍니다.

• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2006.09a
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• pp.3-12
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• 2006

The main feature of these total technologies is that we can constitute the optimum treatment scheme fitting to the property of wastes, amount of wastes and energy requirement. For high moisture content wastes or biomass resources, high pressure steam process (MMCS) for crush, dry and deodorize wastes to produce high quality fertilizer of fuel is most appropriate. For dry or semi-dry solid wastes, the STAR-MEET system can be applied to produce low-BTU gases for power generation using duel fueled diesel engines of Stirling engines, and the REPRES and HyPR-MEET systems can be applied to produce hydrogen rich medium-BTU gas. For waste plastics and oils, liquefaction technology is best fit to produce light oil or kerosene equivalent fuel oils. These total technologies are completely different from the existent waste treatment technologies based on land-filling or incineration, and are expected to disseminate all over the world in the near future.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.163-166
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• 2003

This paper presents the results of a series of performance tests for the Stilting cryocooler. Infrared sensor systems incorporating cryocoolers are required to be qualified to the appropriate environmental specification. Linear drive Stilting cryocooler have matured to the stage of undergoing formal qualification test program The thermal environmental test of the Stilting cryocooler is presented in this paper. We performed that low and high temperature keeping test from －4$0^{\circ}C$ to ＋6$0^{\circ}C$ and operating test at high and low temperature cyclic range with acceptance tests performed at scheduled intervals. Cooling capacity was determined as a function of cooler components temperatures at the compressor, hot end and cold tip. Tests performed on this cooler have been successful with a measured cooling performance of more than 0.8W＠80K for 23$^{\circ}C$ ambient temperature with 40 $W_{ac}$ input power.