• 한국초전도ㆍ저온공학회논문지
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• 제3권2호
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• pp.44-48
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• 2001

SMES consists of Superconducting magnet, a power converter, a cryostat and HTS current leads The prototype cryostat with HTS current leads and refrigerators was designed and manufactured for developing micro SMES. The temperature rise under dc current in HTS current leads was measured. The performances of helium boil-off and mechanical stress were evaluated during transfer and vibration tests. The results will be used to develope the micro-SMES system.

• Journal of Magnetics
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• 제16권3호
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• pp.276-280
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• 2011

This paper presents a non-destructive evaluation study on a radiator with cooling fins as a complex shaped specimen. Radiator structures are used in various heat exchangers, such as automobiles, air conditioners and refrigerators. An eddy current testing method, namely multi-frequency excitation and spectrogram method (MFES), was employed to detect a defect on the radiator tube surrounded by cooling fins. Overall, experimental results suggested that the influence of cooling fin is not as noticeable as that of the defect signals.

• 설비공학논문집
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• 제7권2호
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• pp.249-265
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• 1995

The performance of a refrigerant mixture of propane(R290)/isobutane(R600a) as a substitute for CFC12 was investigated in a domestic refrigerator with single evaporator. A thermodynamic cycle simulation indicated an increase in COP of a 1.7 to 2.4% with R-290/600a in the composition range of 0.2 to 0.6 mass fraction of R290 compared to CFC12. For the tests, two units($299{\ell}$, $465{\ell}$) were used. All refrigeration components remained the same throughout the tests, except that the length of capillary tube and amount of charge were changed for the mixture. The refrigerators were fully instrumented with more than 20 thermocouples, 2 pressure transducers, and watt/watt-hour meter for each refrigerator. 'Energy consumption test' and 'no load pulldown test' were performed under the same condition. The experimental results obtained with the same compressor indicated that R-290/600a mixture at 0.6 mass fraction of R290 showed a 3 to 5% increase in energy efficiency and a faster cooling speed compared to CFC12. The R-290/600a mixture showed a shorter compressor on-time and a lower compressor dome temperature than CFC12. In conclusion, the proposed hydrocarbon mixture seems to be an appropriate candidate to replace CFC12 without causing more environmental problems.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.18-25
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• 2016

대형 압축식 냉동기의 증발기 전열관으로는 그간 평활관이 주로 사용되어 왔으나 최근들어 비등 성능이 우수한 성형 가공관을 많이 사용하고 있다. 증발기는 관군으로 구성되고 따라서 증발기 내 위치에 따라 냉매 상태가 다르다. 특히 R-11, R-123과 같은 저압 냉매는 압력변화에 따른 포화온도 변화가 크므로 위치에 따라 포화온도가 다르게 된다. 따라서 증발기를 적절히 설계하려면 증발기 내 각 위치에서의 냉매의 상태를 적절히 예측하여야 한다. 본 연구에서는 대형 냉동기의 만액식 증발기를 모사할 수 있는 컴퓨터 프로그램을 개발하였다. 이 프로그램은 증발기를 미소 체적으로 구분하고 각 미소 체적에 적절한 관 내외측 열전달 및 압력손실 상관식을 적용하여 해석을 수행하였다. 본 프로그램을 R-123을 사용하는 T사의 만액식 증발기 해석에 적용한 결과 만족할 만한 결과를 얻었다. 이 프로그램을 이용하여 신 냉매인 R-123, R-134a를 사용하는 만액식 증발기의 해석을 수행하였고 특히 관군 세장비의 영향을 검토하였다.

• 한국식품과학회지
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• 제42권3호
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• pp.373-376
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• 2010

본 연구는 국내에서의 가정내 냉장고 온도에 대한 조사를 수행하여, 현 시점에서의 냉장고에서의 식품보관 온도분포를 추정하였고, 이를 MRA(미생물 위해평가: Microbial risk assessment)의 입력변수로 활용할 수 있도록 적정 확률분포 모델을 제시하였다. 일반적으로 가정내 냉장고에서의 식품 보관온도는 식중독 발생 등에서 있어 중요한 위해인자로 작용하는 것으로 알려져 있다. 조사대상 가구는 총 139가구이었으며, 조사기간은 2009년 5월에서부터 9월까지 data logger를 이용하여 측정하였다. 조사된 냉장고 온도의 평균은 $3.53{\pm}2.96^{\circ}C$로, $5^{\circ}C$ 이상은 23.6%로 나타났다. 수집된 온도자료는 @RISK를 이용, 적합성 검정(GOF: K-S와 AD test)을 수행하여 적정 확률분포모델에 대해 추정하였고, 이중 LogLogistic(-10.407, 13.616, 8.6107)분포 모델이 가장 적절한 국내에서의 가정내 냉장고 식품보관 온도분포 모델로 나타났다. 이 확률분포 모델은 MRA적용에 있어 노출평가에서 입력변수로서 직접적 활용이 가능하다고 할 수 있겠다.

• 한국대기환경학회지
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• 제30권1호
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• pp.59-67
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• 2014

In 1995 Kimchi refrigerator was developed at first, and has used HFC-134a as refrigerant. Kimchi refrigerator has been made 1,044,694 on the basis of 2010, disposed about 160,000 per year. Although mobile air conditioning, commercial refrigerator, general refrigerator is regarded as a major source of HFC-134a, little information is available for its emission characteristics of HFC-134a. This paper addresses the fugitive emission factors of Kimchi refrigerator at use-phase and disposal-phase. The residual quantities of Korean-made fifty three waste Kimchi refrigerators were weighed using a commercial recover of refrigerants to determine the emission factors at the disposal-phase. On the other hand, the emission factors at use-phase were estimated from the residual quantities and operating times. The average residual rate of forty three scarp Kimchi refrigerators is determined to be $74.6{\pm}5.2%$. The emission factor at the use-phase is estimated to be $3.5{\pm}0.8%/yr$ as a result of using average age of 11.7 years and the average residual rate determined here. The emission factor at the disposal-phase is determined to be 31.3% after adopting 58% of the recycling rate of refrigerant reported by Recycling Center. We estimate 3.1 g/yr for the average emission quantity of HFC-134a per operating refrigerator, while 22.5 g for that per waste Kimchi refrigerator. Since the chemical compositions of refrigerant of waste Kimchi refrigerator were the same as those of new refrigerant, it is expected that the HFC-134a recovered from waste Kimchi refrigerator can be reused for refrigerant.

• 한국산학기술학회논문지
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• 제12권5호
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• pp.2031-2037
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• 2011

최근의 냉장고 등에 채택되고 있는 프렌치 도어는 2개의 도어를 사용하지만, 내부에 칸막이가 없어 내부 공간을 효율적으로 사용할 수 있는 장점이 있다. 그러나 프렌치 도어는 2개의 도어와 몸체와의 밀폐를 위해 부착된 개스킷이 서로 간섭을 일으키기 때문에 개스킷의 마모로 인해 밀폐성능에 치명적인 영향을 미치고 도어의 개폐력이 증가되는 문제점이 있다. 본 연구에서는 프렌치 도어의 개폐를 위해 4절 링크기구의 동작을 이용한 개폐 메커니즘을 개발하였다. 또한, 개발된 4절 링크기구를 설계 및 제작한 후 실제 냉장고에 적용하여 간섭이 발생하지 않음을 검증하였고, 개방력도 저감됨을 확인하였다. 본 연구에서 제안된 메커니즘은 냉장고뿐만 아니라 프렌치 도어를 채택하는 다른 가전제품이나 산업제품에도 적용될 수 있다.

• 한국소음진동공학회논문집
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• 제22권12호
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• pp.1237-1242
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• 2012

No matter how low it might be, noise from home appliances in indoor environment cause displeasure for residents as it is produced nearby. Electronic goods including vacuum cleaner and washing machine generate high frequency noise, which interrupts TV-watching or conversations and cause noises between floors in apartment houses. In particular, refrigerators make constant noise late at night, hampering the study for exams and causing sleeplessness. Korea, despite the government's efforts to promote low-noise goods based on the noise test by corporation, there is a lack of standardization in the test method, test condition and measuring equipments. This is a major reason that lowers the reliability of low-noise products. At present, low-noise home appliances are certified with eco labeling in the nation but, only 7 brands of refrigerators, 4 brands of washing machines and 97 brands of air-conditioners obtained certification as of august, 2011. In addition, none of Kimchi-refrigerator and vacuum cleaner brands were approved as low-noise home appliances. This shows Korea's relatively underdeveloped market for low-noise products, which, in part, is because of the difficulties companies face in being certified with eco labeling as they should satisfy various requirements such as power-saving and eco-friendly design besides low-noise features. As a result, low-noise labeling for home appliances should be established for the revised noise and vibration management law and the study was carried out to establish low-noise labeling system for major noise sources including vacuum cleaner, washing machine, air-conditioner and refrigerator.

• 한국기계가공학회지
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• 제15권6호
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• pp.129-135
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• 2016

There have been many types of development and commercialization efforts for superconducting power applications with the continuous development of High Temperature Superconducting (HTS) conductors. In particular, HTS power cables are going to be commercialized in real power grids. A cryogenic refrigeration system should be used to keep it below 77 K, and its required cooling capacity continuously increases as the unit length of the HTS power cable increases. Among the many kinds of cryogenic refrigerator, a reverse Brayton refrigerator that uses turbo expanders is a promising refrigerator due to its efficiency and reliability. Among the various components in refrigerators, the cryogenic turbo-expander is the most important part for increasing efficiency and assuring reliability. The design of a 300 W class turbo-expander is described in this paper prior to the development of a 10 kW class turbo expander, which is the required capability for the commercialization of a HTS power cable. The impeller shape and rotation speed are determined based on the cycle analysis. The Eigen frequency and harmonic analysis are conducted with gas bearings at cryogenic temperatures to determine the operational stability.

• 한국소음진동공학회논문집
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• 제26권5호
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• pp.536-545
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• 2016

Household refrigerator radiates noise of which the pattern is dependent on the operating condition of its parts, such as compressor, flow fans, etc. Thus the refrigerator noise has a variety of frequency characteristics. Therefore, it is required to consider the noise characteristics for evaluating the noise quality and eventually developing the sound quality index of the refrigerator noise. In this study, five units of household refrigerator were selected to measure their noises that were used to generate sound sources for jury test of the study. The measured noises of five refrigerators were divided into ten kinds of sound source by considering operating condition and frequency characteristics. Additionally, the ten sources were each edited to have the same SPL of 30 dBA. Totally twenty kinds of sound sources (10-original SPL, 10-edited SPL 30 dBA) were evaluated by twenty-two subjects, and compared with their sound quality metrics. It was found that only the loudness of the metrics was meaningfully correlated with the subjective evaluation. The rests, sharpness, roughness and fluctuation strength, were not related. The conclusion of this study is that a new sophisticated index is necessary to be developed to qualitatively evaluate the household refrigerator noise.