• The Journal of the Acoustical Society of Korea
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• v.14 no.6
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• pp.5-12
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• 1995

In this paper, acoustic analysis of thermoacoustic refrigerating system was given and the design procedure meeting the specifications was presented. The thermoacoustic refrigerator transforms the sound wave energy into the thermal energy via adiabatic process of inert gas. The system is composed of mainly three parts ; the acoustic motor utilizing loudspeaker the stack of plate for thermal transport and the resonator to form the standing wave. Based upon the acoustic analysis, resonator dimension and stack position and size were decided, and the entire refrigerating system was designed to the given specification. Also the mechanical Impedance of the designed resonator was obtained by simulation.

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.26-32
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• 2021

In the process of vaccine delivery and vaccination, temperature is mostly controlled by an insulated containers containing ice. Moreover, amount of wasted vaccine is significant because the temperature of the vaccine is not properly controlled. A core challenge of vaccination is temperature data monitoring, since it is critical for managing and operating strategical vaccination by health organizations. In this research, a real-time monitoring vaccine carrier system was developed. Temperature, location, and power consumption data of the vaccine carrier were monitored and working performances of the vaccine carrier were tested in both Korea and Tanzania (Arusha and Kilimanjaro regions). For both places, Short Message Service (SMS) communication method was used to send information of the carrier's status. As a result, the monitoring system was able to transmit and receive real-time data of the vaccine carrier status while the vaccine carrier was tested. The vaccine status data can be accessed from any location through the cloud server and web-based user interface.

• The Korean Journal of Food And Nutrition
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• v.28 no.3
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• pp.422-427
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• 2015

This study was carried out to investigate the microbiological contamination levels of Dutch coffee products marketed in Korea. The temperature conditions during distribution and storage were also considered in this experiment. Retailed Dutch coffee were purchased from regional cafes, that is, these were self-blended by the cafes, and the marketed products were purchased from department stores and from Internet sites. The 21 samples were blended in a coffee house and 9 were obtained from department stores or were delivered from internet sites. House blended Dutch coffee contained $35.2{\pm}15.8CFU/mL$ of general bacteria, and this increased to $78.4{\pm}29.7CFU/mL$ at room temperature or $51.2{\pm}32.1CFU/mL$ after refrigeration for 5 days. These almost reached the highest criteria level for the Korea Food Sanitation Law. After 10 days, the count increased to $98.5{\pm}58.4CFU/mL$ at room temperature and $86.7{\pm}44.2CFU/mL$ at refrigeration temperature. In the Dutch coffee for distribution, $39.6{\pm}20.1CFU/mL$ of general bacteria were detected, but these did not increase after 5 days or 10 days both for room temperature and under refrigeration. The Coliform group was not found in any kind of Dutch coffee, and Fungi was founded in 60% of the Dutch samples purchased in coffee houses, department stores, and shopping sites mall. On day 0 day, $2.6{\pm}1.7CFU/mL$ of fungi were detected in the coffee house Dutch, and it did not increase significantly during the storage period at room and in a cold temperature. $3.5{\pm}3.4CFU/mL$ of fungi were detected in the Dutch coffee for distribution, and it didn't increase during further storage under any temperature.

• Food Science and Preservation
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• v.23 no.2
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• pp.155-161
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• 2016

This study aimed to investigate the effects of pretreatments blanching, roasting, drying, and storage temperatures ($25^{\circ}C$, $4^{\circ}C$ and $-10^{\circ}C$) on their quality of lotus leaves. As a result, the lotus leaves retained a good appearance when stored at $25^{\circ}C$ for 5 days, $4^{\circ}C$ for 30 days, and $-10^{\circ}C$ for 90 days, regardless of the pretreatment used. At the same storage temperatures, pH, soluble solids, total acid content, polyphenols, and microorganisms were significantly different among the pretreatments (p<0.05). Soluble solids, pH, and total acid contents were not significantly different for the same pretreatments at different storage temperatures. However, the polyphenol, oxalic acid, and tartaric acid contents of lotus leaves were significantly different after drying and blanching treatments. In particular, it was shown that polyphenol content of the lotus leaf was affected by both pretreatment and storage temperature. In conclusion, the lotus leaves appeared in good condition until 5 days at $25^{\circ}C$, 30 days at $4^{\circ}C$, and 90 days at $-10^{\circ}C$, regardless of the pretreatment while influenced by storage temperature.

• The Korean Journal of Pesticide Science
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• v.13 no.3
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• pp.127-132
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• 2009

The purpose of this study is to examine changes in the pesticides residues in pepper powder by storage conditions. Analysis of pesticide residues was performed using multiresidue analytical methods and the number of pesticides detected from 60 pepper powders was 7 pesticides such as cypermethrin, fenvalerate, kresoxim-methyl, chlorpyrifos, chlorfenapyr azoxystrobin, tebuconazole. The concentrations of cypermethrin and tebuconazole were exceeded their maximum residue limits (MRLs). The degradation patterns of pesticides at $-5^{\circ}C$ were compared to those at $20^{\circ}C$ and $4^{\circ}C$. Without reference to storage temperature, degradation rates of azoxystrobin and fenvalerate were above 80%. Degradation rate of chlorpyrifos was 47% at storage $4^{\circ}C$, $20^{\circ}C$ and 34% at storage $-5^{\circ}C$. During each storage peroid, the degradation patterns were more lower at $-5^{\circ}C$ than at $20^{\circ}C$ and $4^{\circ}C$.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.12
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• pp.98-103
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• 2019

With the increasing need for environmental protection, it is particularly important to improve the energy saving and reliability of refrigerators. Generally, the cold air flowing into the freezer compartment transits to the bottom of the refrigerating compartment, which can lead to uneven temperature distribution. This paper proposes two design solutions for improving the temperature distribution problem. Of these, the optimal refrigeration design was selected and tested using Computational Fluid Dynamics (CFD) modeling and simulation. The results showed improved uniformity of the temperature distribution inside the refrigerator, thus benefitting food storage while reducing energy consumption.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.2
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• pp.249-255
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• 2013

A large-sized refrigerator has a complicated inner structure such as a shelf and a rack for product loading. Therefore, when the refrigerator door is opened and closed, the temperature inside the refrigerator varies and vibrations occur due to the physical force applied for opening and closing the door. Owing to these factors, an abnormal sound is generated by the relative distortion between the inner structures. In this study, we aimed to clarify the mechanism that generates this abnormal noise inside the refrigerator using experimental approaches, and we also investigated ways by which to reduce this noise. Toward this end, we developed an experimental setup for measuring the noise, temperature, inner pressure, as well as amount of vibration, and we analyzed the main factors causing the noise based on the experimental results. Furthermore, we suggested a way by which to reduce the noise; this method can be applied in the design stage itself.

• Journal of Food Hygiene and Safety
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• v.26 no.4
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• pp.283-288
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• 2011

We surveyed the sanitary conditions for 17 cold and frozen food storage warehouses in Korea, using the following 5 inspections items: "putting into warehouse (A)", "prevention of cross-contamination (B)", "storage management (C)", "temperature control (D)", and "management of records and documents (E)", We included 20 detailed items. The results of distribution for frequency by five major inspection items showed that "(E)" was the highest, the next "(D)", "(C)"; and "(B)" was the lowest. In the correlation of inspection scores between total scores, "(B)" and "(C)" were highly related to the total score, therefore, the higher score of "(B)" or "(C)", the higher for the total score. In details of inspection items, "the management of cross-contamination upon taking product out of the warehouse" had the lowest score with a mean, of $2.67{\pm}1.80$, and also ranked as first of the 20 items.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.04a
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• pp.148-154
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• 1996

가정용 냉장고에 있어서 정음화를 위한 다각적인 노력이 냉장고의 주요 소음원이라고 할 수 있는 압축기, 냉기 순환용 팬, 압축기 냉각용 팬 및 냉매 순환용 파이프 방진구조 등의 개선을 통하여 국내외적으로 상당한 진척을 보이고 있다. 이러한 소음원들의 특징은 각각이 특정한 목적에 의하여 작동하는 하나의 구동부이거나 이러한 구동부와의 직접적인 연결에 의해 가진되는 경우로서 Airborne Noise나 Structureborne Noise를 발생시키고 있다. 본 논문에서는 이러한 압축기나 팬이 꺼진 상태에서 냉장고의 싸이클상에 열교환용 냉매가 봉입된 상태에서 압축기가 운전시 형성되었던 싸이클상의 고압 및 저압측의 압력 차이에 의하여 증발기의 Accumulator내에 형성된 Sleeve(이하, 삽입관 .PHI.1.5 Hole)에 의해서 발생되는 Bubble 소음에 대한 실험적 규명과 소음 측정을 통한 주파수 분석을 하였으며, 이러한 Bubble 소음 발생시 싸이클상의 온도 및 압력값을 측정하여 Strasberg에 의해 도출된 선형화된 식을 이용하여 Bubble 소음 발생시 주파수 분석을 통한 Bubble Size를 결정하였고, Bubble 소음 발생의 직접적인 원인으로 작용하는 Orifice를 제거하여 Bubble 소음의 개선 정도를 비교 검토하였다.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.05a
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• pp.206-210
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• 2004

본 연구는 국내 조건에서 살라미를 생산하였을 때 현행 국내 육제품의 위생 기준을 만족시킬 수 있는지 여부와 살라미 저장 중 미생물학적 품질 변화를 살펴보기 위하여 실시되었다. 살라미 원료육에서는 Staphylococcus aureus와 대장균군이, 그리고 살라미 제품 중 한 시료에서 Clostridium perfringens가 검출되었다. 살라미의 저장 중 냉장온도($10^{\circ}C$)보다 실온($25^{\circ}C$)에서 균수의 감소가 두드러졌다. 제품의 저장 중 대장균군은 발견되지 않았다. 종합적으로 판단해 볼 때 살라미에서의 병원성 미생물에 대한 음성 기준을 만족시키기는 현실적으로 어렵다고 판단되므로 관련 기준의 완화가 요구된다.