• 한국정밀공학회지
• /
• 제33권6호
• /
• pp.517-523
• /
• 2016

Unlike household refrigerators, commercial refrigerators are composed of separate indoor and outdoor units. The outdoor unit of most commercial refrigerators is designed to run at a fixed speed, which results in low energy efficiency and loud fan noise. Moreover, it cannot respond flexibly to changing thermal load in the indoor unit. Inverter type outdoor units can address such problems through speed changes based on information obtained from the indoor unit. However, using two units from different manufacturers is often not a viable solution. If condition changes in the indoor unit can be detected without communication between the two units, it is possible to adjust the speed of the outdoor unit. This paper attempts to analyze the signal from the outdoor unit when the condition of the indoor unit changes by varying the thermal load.

• 한국생활과학회지
• /
• 제14권4호
• /
• pp.693-707
• /
• 2005

This study investigates the over time changes in the ownership of kitchen items, electric or non-electric, and examines the patterns of the usage and ownership of the items after categorizing them as followings: cooking appliances, kitchen appliances directly related to storing food, food processing kitchen items, and dining items. The research findings are that refrigerators and rice cookers, among the electric items, had spread to almost every households by 1990s and at the same time about thirty non-electric kitchen items had been used. Refrigerators had been used by more than 100% of the households by 2000, and on top of that, twenty or more electric kitchen items such as Kimchi fridge and freezer had been used. In the case of non-electric kitchen items, approximately 50 to 70 sorts of them are used, which indicates an increase than in 1990s. Rice cookers and gas stoves, among cooking appliances, are recognized as the essential item, and they are actually frequently-used items. As to kitchen appliances related to storing food, each household owns one of the refrigerators and Kimchi fridges, and again they are both the frequently-used. As far as food processing kitchen items are concerned, each household owns at least one or more blenders and hand blenders, six or more knives, and five or more pans. Each household owns seventeen or more rice bowls and soup bowls and twenty-four or more plates. Small plates are more frequently used than large ones.

• 대한전자공학회논문지SP
• /
• 제46권5호
• /
• pp.80-90
• /
• 2009

본 논문에서는 냉장고로부터 방사되는 소음에 대한 사용자의 불쾌도를 객관적으로 평가하기 위한 방법을 제안하였다. 이를 위해 8개의 상용 냉장고로부터 방사되는 소음이 무향실과 아파트로부터 녹음되었다. 사용자가 냉장고 소음으로부터 느끼는 주관적 청감을 알아보기 위하여 100명의 평가자로부터 청감 실험을 통하여 각 냉장고 소음의 주관적 평가 데이터가 얻어졌다. 그리고 이로부터 심리 음향 속성을 나타내는 파라미터인 5개의 Sound Quality Metric (SQM) 도출하였다. 마지막으로 주관적 소음 평가 데이터와 5개의 객관적 SQM 값 사이에 높은 상관도를 부여하는 냉장고 소음에 대한 객관적 평가 모델이 제시된다.

• 한국디자인학회:학술대회논문집
• /
• 한국디자인학회 2001년도 Bulletin of The 5th Asian Design Conference International Symposium on Design Science
• /
• pp.61.2-61
• /
• 2001

• 동력기계공학회지
• /
• 제13권2호
• /
• pp.49-55
• /
• 2009

Recently, a study on condensers for refrigerators has focused on new model which will cost less and will be more efficient. Some widely used condensers for domestic refrigerators are wire-and-tube type condenser, hot-wall type condenser, and spiral type condenser. Some companies which use the spiral type condenser at the moment try to develop a new tube-and-plate type condenser which will cost less and will be as efficient as the spiral type. As a standard condenser type, tube-and-plate type condenser is used in this study. A two-dimensional numerical model for the tube-and-plate type condenser is proposed, and the flow and heat transfer characteristics for several types of condensers are investigated.

• 설비공학논문집
• /
• 제9권2호
• /
• pp.239-248
• /
• 1997

Steady components and unsteady components of second-order velocity and temperature within pulse tube refrigerators were obtained. Second-order solutions were obtained from the first-order solutions of continuity, momentum and energy equations, assuming that the amplitude of the piston motion is small. The axial temperature gradient was considered in the analysis. The flow direction of the streaming was consistent with previous experimental observations. Effects of axial temperature gradient on secondary flow and second-order temperature were shown.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 춘계학술대회논문집D
• /
• pp.304-310
• /
• 2001

A numerical model which simulates the heat and mass transfer processes within a counter-current plate type generator for ammonia/water absorption refrigerators was developed. Ammonia/water solution flows downward under gravity and ammonia/water vapor generated by flow boiling flows upward. The flow pattern within the generator was assumed to be a bubbly flow, and the liquid and vapor phase were assumed to be saturated. It was shown that the boiling of ammonia occurred mainly in the upper part of the generator. The effects of the generator length, the wall temperature and the mass flow rate of ammonia/water solution into the generator on the generation of ammonia/water vapor were investigated.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2004년도 추계학술대회
• /
• pp.1312-1316
• /
• 2004

The Stirling refrigerators have been widely used for the cooling of the infrared detector and HTS to the cryogenic temperature. The Stirling refrigerator with the rotary compressor are applicable to the cooling device for the compact mobile thermal imaging system, because the refrigerators have the compact structure and light weight. The typical performance factors of the Stirling refrigerator are the cool-down time, cooling capacity at the desired temperature and the input power. And the above performance factors are depends on the thermal insulation characteristics of the Dewar. In this study, the steady thermal load of the Dewar and the performance of the Stirling refrigerator were measured. The results show the dependency of the input power and the charging pressure on the performance of the refrigerator.

• Journal of Mechanical Science and Technology
• /
• 제20권12호
• /
• pp.2013-2024
• /
• 2006

This paper proposes a condition classification system using wavelet transform, feature evaluation and artificial neural networks to detect faulty products on the production line of reciprocating compressors for refrigerators. The stationary features of vibration signals are extracted from statistical cumulants of the discrete wavelet coefficients and root mean square values of band-pass frequencies. The neural networks are trained by the sample data, including healthy or faulty compressors. Based on training, the proposed system can be used on the automatic mass production line to classify product quality instead of people inspection. The validity of this system is demonstrated by the on-site test at LG Electronics, Inc. for reciprocating compressors. According to different products, this system after some modification may be useful to increase productivity in different types of production lines.

• Journal of Electrical Engineering and Technology
• /
• 제12권6호
• /
• pp.2317-2323
• /
• 2017

Recently, linear compressors of cooling systems such as refrigerators, which have a free piston driven by a linear motor, have attracted much attention because of their high efficiency. For structural reasons, linear compressors applied in refrigerators should use an AC capacitor to ensure stable control. However, AC capacitors are expensive and bulky. In this paper, we propose a new method to realize stable control without a real AC capacitor by implementing a virtual AC capacitor with software. To realize a virtual AC capacitor, a pure integral is calculated. Nonetheless, if an offset current exists, the calculation may diverge to infinity. To solve this problem, a high-pass filter is applied and the compensation for the phase angle and magnitude are realized with a new method. Finally, a virtual AC capacitor enables variable frequency operations. Hence, in case of a lack of voltage, we can compensate by running the linear compressor in high-frequency operations. To improve efficiency, we may optimize the operation frequency. The validity of a virtual AC capacitor has been verified through simulations and experimental results.