• Transactions of the Korean Society of Mechanical Engineers B
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• v.32 no.5
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• pp.359-366
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• 2008

A two-dimensional thermal model of proton exchange membrane fuel cell with large active area is developed to investigate the performance of fuel cell with large active area over various thermal management conditions. The core sub-models of the two-dimensional thermal model are one-dimensional agglomerate structure electrochemical reaction model, one-dimensional water transport model, and a two-dimensional heat transfer model. Prior to carrying out the simulation, this study is contributed to set up the operating temperature of the fuel cell with large active area which is a maximum temperature inside the fuel cell considering durability of membrane electrolyte. The simulation results show that the operating temperature of the fuel cell and temperature distribution inside the fuel cell can affect significantly the total net power at extreme conditions. Results also show that the parasitic losses of balance of plant component should be precisely controlled to produce the maximum system power with minimum parasitic loss of thermal management system.

• Journal of Korean Institute of Industrial Engineers
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• v.39 no.4
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• pp.247-252
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• 2013

Korea gas corporation (KOGAS) is responsible for the whole sale of natural gas in the domestic market. It is important to forecast the daily demand of city gas for supply and demand control, and delivery management. Since there is the autoregressive characteristic in the daily gas demand, we introduce a modified autoregressive model as the first step. The daily gas demand also has a close connection with the outdoor temperature. Accordingly, our second proposed model is a temperature-based model. Those two models, however, do not meet the requirement for forecasting performances. To produce acceptable forecasting performances, we develop a weighted average model which compounds the autoregressive model and the temperature model. To examine our proposed methods, the forecasting results are provided. We confirm that our method can forecast the daily city gas demand accurately with reasonable performances.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.4
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• pp.601-607
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• 2008

This study was examined the preferred temperature and salinity of soup in various demographic groups in order to establish the desirable serving renditions of soup for customers' satisfaction and health. Temperature and salinity were measured in August and November in order to determine the seasonal variation in preference using a digital salinity-temperature measuring device. Four demographic groups totaling 530 were from foodservice establishments in elementary schools(ES: male 68/female 59), middle-high schools(MHS: 62/69), universities(UNIV: 72/67) and companies(COM: 69/64) in Seoul. Various thin or thick soups which are typically served in foodservice establishments were served hot(below $90^{\circ}C$) and warm(below $40^{\circ}C$) in a 50mL portion: salty(1.2%) and less salty(0.4%) at $55{\pm}2^{\circ}C$. The preferred salinities and temperatures of the soups were found to be 0.74%, 0.82%, 0.64% and 0.67% and $49.65^{\circ}C$, $54.24^{\circ}C$, $57.56^{\circ}C$, $58.81^{\circ}C$ for the ES, MHS, UNIV and COM groups, respectively. The preferred temperatures of the soups were increased depending on the age, so the positive correlation was shown between temperature and age. However the preferred salinities of soups were not effected. There was no consistent tendency between men and women in temperature. For salinity, men preferred $0.04{\sim}0.12%$ higher than women in the ES, MHS and UNIV groups. There is no consistent tendency between thin and thick soup in temperature. All groups preferred higher salinity in the thick soup than in the thin soup. Most of the customers preferred a higher temperature and higher salinity in November than in August.

• Proceedings of the Korean Society for Quality Management Conference
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• 1998.11a
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• pp.361-377
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• 1998

The measurement of welding temperature of connector is usually performed with an infra red temperature gauge. However, the factors, which influence the temperature measurement, are rarely known. This research used the welding temperature measurement of the connector as an example, applying the experimental design, in two-phase experiments, to search the affecting factors. In phase-I experiment, we used a resolution III, seven-factor fractional factorial design with two levels for each factor. The result showed that none of the factor was significant in affecting the welding temperature when the type I error ${\alpha}$ was 0.05. Next, we did the phase-II factorial experiment with three factors and each factor had three levels. The experiment showed the experimental time was significant in affecting the temperature measurement when the type I error ${\alpha}$ was 0.05. Further Duncan's multiple range tests on the second experimental data showed that the later the experimental time, the weaker the light intensity could have on the temperature measurement and the average of the highest temperatures was lower. Moreover, the later the experimental time, the smaller was the variance of the temperature measurement and the difference between the averages of the highest and the lowest temperatures was also lower.

• Journal of the Korea Safety Management & Science
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• v.19 no.4
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• pp.149-155
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• 2017

This study is analyzed combustion phenomena based on the environmental energy facility incinerator. It is assumed that combustible components of waste are composed of carbon and hydrogen, and the combustion process of fuel is by setting as multi-component / multistage reaction. As the combustion chamber is burned, the high temperature environment is achieved, also the heat transfer accompanied by the turbulent flow and the generation of NOx, a pollutant, are interpreted to predict the thermal and fluid characteristics and pollution emissions of the grate incinerator. As the result of internal flow analysis, the slow flow around the ash chute and the mixing effect due to the complicated turbulence around the combustion chamber were predicted to show excellent performance. It is shown to the internal average temperature was about $1024^{\circ}C$, around the about $1000^{\circ}C$ homogeneous temperature distribution. Due to the sudden temperature decrease in the boiler, the flue gas temperature at the outlet was estimated to be about $220^{\circ}C$.

• Journal of the Korean Society of Visualization
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• v.21 no.2
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• pp.34-45
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• 2023

When lithium-ion batteries operate out of the proper temperature range, their performance can be significantly degraded and safety issues such as thermal runaway can occur. Therefore, battery thermal management systems are widely researched to maintain the temperature of Li-ion battery cells within the proper temperature range during the charging and discharging process. This study investigates the cooling performance and isothermal maintenance of cooling materials by measuring the surface temperature of a battery cell with or without cooling materials, such as silicone oil, thermal adhesive, and phase change materials during discharge process of battery by the experimental and numerical analysis. As a result of the experiment, the battery pack filled with phase change material showed a temperature reduction of 47.4 ℃ compared to the case of natural convection. It proves the advanced utility of the cooling unit using phase change material that is suitable for use in battery thermal management systems.

• Journal of the East Asian Society of Dietary Life
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• v.18 no.2
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• pp.264-275
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• 2008

Seven constructs of sanitary management were evaluated in order to examine perceived performance of sanitary management and sanitary recognition for school food service managers in the Kyunggido area. In order to protect from foodborne illness, 331 (58.4%) responded that the most important aspects were sanitary conditions and stability upon food delivery, and the greatest obstacle was limited availability of facilities and equipment (182, 32.2%). The total mean score for the perceived performance of sanitary management was $4.16{\pm}0.445$ (5-point Likert scale). Among three sectors, personal hygiene management was generally well-conducted with a subtotal mean score of $4.52{\pm}0.458$; however temperature management scored lowest with a subtotal mean of $3.71{\pm}0.630$. Chi-square tests were performed according to general characteristics on the two lowest perceived sanitary management performance areas. In temperature management, there was a significant difference in 5 sectors according to age, and the ages $20{\sim}29$ showed the best perceived performance in all sectors. For serving management, a significant difference (p<0.01) was shown in all sectors. In conclusion, foodservice managers perceive that sanitary management is well-executed. However, the combination of proper equipments and facilities would lead to better perceived management.

• Journal of the Korea Safety Management & Science
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• v.10 no.4
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• pp.121-126
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• 2008

The effect of $Al(OH)_3$ on physical, thermal, and retardant property of rubber was studied. It was analyzed by statistical experimental design method with one way array to confirm the effect of factors. Physical characteristics, thermal pyrolysis temperature, and combustion time were considered as the properties. The amount of $Al(OH)_3$ addition was chosen as significant parameter. As the result of ANOVA analysis, thermal pyrolysis temperature increased and combustion time decreased with increasing of $Al(OH)_3$.

• Journal of Korean Society for Quality Management
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• v.45 no.3
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• pp.447-462
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• 2017

Purpose: This study aims to develop distributable samples that can be used for proficiency testing to verify the ability of the testing laboratory to perform high temperature and low temperature tests. Method: In this study, the temperature-resistance characteristics of the NTC thermistor were used to develop samples. The homogeneity and stability of samples were examined according to the proficiency testing requirements. Results: Thirty samples with homogeneity and stability were developed and used for the proficiency testing. Thus, it was possible to distinguish between the test laboratories that showed satisfactory results and those that did not. Conclusion: It was the first time to develop samples that can be used for proficiency testing in high temperature and low temperature tests. and it was proved that the proficiency test program can be operated using the characteristics of NTC thermistor.

• KCI Concrete Journal
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• v.14 no.2
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• pp.81-85
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• 2002

The strength development of concrete is influenced by temperature and cement type which greatly affect hydration degree of cement. There is not pertinent concrete strength management method in korea. There are several methods for estimating the in-place strength of concrete. One such method is the maturity concept. The maturity concept is based on the fact that concrete gains strength gradually as a result of chemical reactions between cement and water; and for a specific concrete mixture, strength at any age and at normal conditions is related to the degree of hydration. The rate of hydration and, therefore, strength development of a given concrete will be a function of its temperature. Thus, strength of concrete depends on its time-temperature history. The goals of the present study are to investigate a relationship between strength of high-strength concrete and maturity that is expressed as a function of an integral of the curing period and temperature and predict strength of concrete.