• Proceedings of the Korea Electromagnetic Engineering Society Conference
• /
• 2003.11a
• /
• pp.140-144
• /
• 2003

To investigate failure analysis of surface acoustic wave (SAW) filter for radio frequency, high temperature storage test was carried out. The failure criteria were insertion loss at passband and rejection level at stopband. As a result, the insertion loss at passband increase about 4 dB was due to damages of interdigital transducer (IDT). That is caused by poor adhesion between metal electrode(AI) and piezoelectric substrate and defects on a manufacturing process. This result indicates that good adhesion between electrode and ceramic substrate is important factor And also we investigated the demage factors of electrode. Screen possible of saw filter using high temperature storage test(HTOL) in the manufacturing phase be presented.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.4
• /
• pp.1-10
• /
• 2015

The light emitting diodes(LED) package of new structure is proposed to promote the reliability and lifespan by maximize heat dissipation occurred on the chip. We designed and fabricated the LED packages mixing the advantages of chip on board(COB) based on conventional metal printed circuit board(PCB) and the merits of Si sub-mount using base as a substrate. The proposed LED package samples were selected for the superior efficiency of the material through the sealant properties, chip characteristics, and phosphor properties evaluations. Reliability test was conducted the thermal shock test and flux rate according to the usage time at room temperature, high-temperature operation, high-temperature operation, high-temperature storage, low-temperature storage, high-temperature and high-humidity storage. Reliability test result, the average flux rate was maintained at 97.04% for each items. Thus, the Si sub-mount based LED package is expected to be applicable to high power down-light type LED light sources.

• Nuclear Engineering and Technology
• /
• v.55 no.10
• /
• pp.3581-3590
• /
• 2023

High-temperature design evaluations were conducted on Type 316L stainless steel piping for a 700 ℃ large-capacity thermal energy storage verification test loop (TESET) under construction at KAERI. The hot leg piping with sodium coolant at 700 ℃ connects the main components of the loop heater, hot storage tank, and air-to-sodium heat exchanger. Currently, the design rules of ASME B31.1 and RCC-MRx provide design procedures for high-temperature piping in the creep range for Type 316L stainless steel. However, the design material properties around 700 ℃ are not available in those rules. Therefore, a number of material tests, including creep tests at various temperatures, were conducted to determine the insufficient material properties and relevant design coefficients so that high-temperature design on the 700 ℃ piping may be possible. It was shown that Type 316L stainless steel can be used in a 700 ℃ high-temperature piping system of Generation IV reactor systems or a renewable energy systems, such as thermal energy storage systems, for a limited operation time.

• Journal of the Microelectronics and Packaging Society
• /
• v.23 no.3
• /
• pp.43-49
• /
• 2016

Reliability characteristics of thin package-on-packages were evaluated using T/H (temperature/humidity) test at $85^{\circ}C/85%$ for 500 hours, TC (temperature cycling) test at $-40{\sim}100^{\circ}C$ for 1,000 cycles, and HTS (high temperature storage) test at $155^{\circ}C$ for 1,000 hours. The average resistance of the solder-bump circuitry between the top and bottom packages of 24 package-on-package (PoP) samples, which were processed using polyimide thermal tape, was $0.56{\pm}0.05{\Omega}$ and quite similar for all 24 samples. Open failure of solder joints did not occur after T/H test for 500 hours, TC test for 1,000 cycles, and HTS test for 1,000 hours, respectively.

• Proceedings of the KSME Conference
• /
• 2008.11a
• /
• pp.1391-1393
• /
• 2008

In this paper, the long-term reliability for 1.25G transceiver in use of high speed optical access network is investigated. High temperature storage tests and accelerated life tests are used to long-term reliability. Accelerated aging test have been during 3,000 hour of the three accelerated aging conditions by caused high temperature stress. Mean life is assumed to follow the Arrhenius relationship and analysis from the failure data obtained in the accelerated aging conditions.

• Proceedings of the Korean Society for Agricultural Machinery Conference
• /
• 2000.11c
• /
• pp.676-683
• /
• 2000

For high quality storage of agricultural products, temperature, humidity and gas conditions in a storage house should be controlled properly. But most of the low temperature storage house is depending on temperature control. This study aimed to develop an automatic control system for low temperature storage house that can control storage conditions such as temperature, humidity and $CO_2$ gas concentration. The developed system alarms the user, by telephone or beeper, when abnormal condition has occurred. The farmer can also monitor the inside condition of warehouse in his residence, by Internet. From the results of the performance test, the temperature and relative humidity in the warehouse is controlled within the range of ${\pm}0.5^{circ}C$ and ${\pm}2%$, respectively.

• Journal of the Korean Society of Food Culture
• /
• v.35 no.5
• /
• pp.450-458
• /
• 2020

This study examined the optimal temperature and time conditions to maintain high quality Dongchimi during the fermentation and storage period. Dongchimi was fermented at low (5℃), medium (10 and 15℃), and high (20℃) temperatures until the acidity reached 0.2, 0.3, and 0.4%. respectively. From the consumer's preference test enrolling five consumers, Dongchimi fermented at 15℃ until an acidity of 0.3% (for approximately six days) was evaluated to be the optimal status because of its high score of overall acceptance, taste, and odor of consumers. To determine the optimal storage temperature of fermentation, Dongchimi was stored at three different temperatures (-1, 2, 5℃) for four weeks after fermenting at 15℃ for six days. During the storage period, most of the physicochemical properties (pH, acidity, reducing sugar content, and organic acid) and microbiological properties changed significantly in the 2 and 5℃ groups, resulting in a significant change in descriptive sensory analysis of Dongchimi. These results indicate that fermentation at 15℃ and storage at -1℃ for Dongchimi enables it to maintain the best quality for a long time.

• Journal of the Korean Chemical Society
• /
• v.65 no.2
• /
• pp.145-150
• /
• 2021

The present study describes a hands-on experiment to help students understand the concept of phase change or phase transition and its application in a phase change material (PCM). PCMs are substances that have the capability of storing and releasing large amounts of thermal energy. They act as energy storage materials that provide an effective way to save energy by reducing the electricity required for heating and cooling. Lauric acid (LA) was selected as an example of the PCM. Students investigated the temperature change of LA and the temperature (of air) inside the test tube. The differences in the temperatures of the systems helped students understand how PCMs work. A one-group pretest and posttest design was implemented with 34 grade-11 students in science and mathematics. Students' understanding was assessed using a multiple-choice test and a questionnaire. The findings revealed that the designed activity helped students understand the concept of phase change and its application to materials for thermal energy storage.

• Journal of Applied Reliability
• /
• v.16 no.3
• /
• pp.238-244
• /
• 2016

Purpose: Domestic electric railway Regenerative Energy Storage System seriously affects the maintenance cost of the total operating expenses of nearly 60% of the total LCC (Life Cycle Cost) due to high dependence on foreign Leading company. Therefore by developing the system, it is important to lower the maintenance cost in the domestic supply. This study about the capacitor Reliability test and the purpose of this study is development electric railway Regenerative Energy Storage System. Methods: In case of, having a close relation between the temperature and the reaction rate, Accelerated Model was known that according to Arrhenius' law of chemical activity. If you apply this formula in using allowable temperature range of the capacitor can induce the Arrhenius empirical formula used in much Manufacture Fields. We evaluate the capacitors Leading company through the Arrhenius model. in order to providing a base for the localization of Ultra Capacitor. Conclusion: In this paper, we conducted a reliability test. And it was performed by the accelerated life test and Cycle Test with temperature and C-rate. and then MTBF and B10 life are estimated by analyzing the accelerated life test result. This is thought to need detailed study applying complex stress than about whether it matches the actual behavior in electric railway.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2012.05a
• /
• pp.259-261
• /
• 2012

The effect of high-temperature on the flexural modulus of epoxy resin were evaluated using universal testing machine with 3-point bending and dynamic mechanical analyzer. Temperatures of $30^{\circ}C$, $100^{\circ}C$, and $140^{\circ}C$ were considered for flexural test. The specimens having aspect ratio of 16, 32, and 40 were used. The results of storage modulus from DMA were similar to those from flexural test along with given temperatures. It is found that the flexural modulus increased with increasing aspect ratio and the specimen having aspect ratio of above 32 would be suitable for the evaluation of composite material properties under high temperature condition.