• The Journal of Korean Medicine
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• v.42 no.4
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• pp.185-196
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• 2021

Objectives: Many symptoms of cold and heat patterns are related to the thermoregulation of the body. Thus, we aimed to study the association of cold and heat patterns with anthropometry/body composition. Methods: The cold and heat patterns of 2000 individuals aged 30-55 years were evaluated using a self-administered questionnaire. Results: Among the anthropometric and body composition variables, body mass index (-0.37, 0.39) and fat mass index (-0.35, 0.38) had the highest correlation coefficients with the cold and heat pattern scores after adjustment for age and sex in the cold-heat group, while the correlation coefficients were relatively lower in the non-cold-heat group. In the cold-heat group, the most parsimonious model for the cold pattern with the variables selected by the best subset method and Lasso included sex, body mass index, waist-hip ratio, and extracellular water/total body water (adjusted R² = 0.324), and the model for heat pattern additionally included age (adjusted R² = 0.292). Conclusions: The variables related to obesity and water balance were the most useful for predicting cold and heat patterns. Further studies are required to improve the performance of prediction models.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.88-97
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• 2018

Computer modeling and optimization works have been performed for the separation of the binary mixture of 1-propanol and benzene through a pressure-swing distillation. PRO/II with PRIVISION V10.0 at Schneider Electric company and NRTL liquid activity coefficient model were utilized. The sum of the total reboiler heat duties of the low-high and high-low pressure column configurations were compared. To minimize the utility consumptions, low column, and high column to obtain pure benzene at the top, the number of theoretical stages and optimal feed tray locations for each distillation column were determined and the reflux ratios for each distillation column were also adjusted. As a result of the optimization works, the sum of the total reboiler heat duties for the high-low and low-high pressure configurations were $3.10{\times}10^6kcal/h$ and $2.75{\times}10^6kcal/h$, respectively. In the case where heat integration was applied to low-high pressure configurations, 57.36 % of the total reboiler heat duties could be saved compared to the high-low pressure configurations.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.2
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• pp.61-67
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• 2017

As transistor density increases rapidly, a heat flux from IC device rises at fast rate. Thermal issues raised by high heat flux cause IC's performance and reliability problems. To solve these thermal management problems, the conventional cooling methods of IC devices were reached their thermal limit. As a result, alternative cooling methods such as liquid heat pipe, thermoelectric cooler, thermal Si via and etc. are currently emerging. In this paper microchannel liquid cooling system with TSV was investigated. The effects of 2 coolants (DI water and ethylene glycol 70 wt%) and 3 metal bumps (Ag, Cu, Cr/Au/Cu) on cooling performance were studied, and the total heat flux of various coolant and bump cases were compared. Surface temperature of liquid cooling system was measured by infrared microscopy, and liquid flowing through microchannel was observed by fluorescence microscope. In the case of ethylene glycol 70 wt% at $200^{\circ}C$ heating temperature, the total heat flux was $2.42W/cm^2$ and most of total heat flux was from liquid cooling effect.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.1
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• pp.63-72
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• 1995

Convective heat transfer in a two-dimensional horizontal and vertical channel with isothermal rectangular beams attached to one adiabatic wall is investigated from the numerical solution of Navier-Stokes and energy equations. The solutions have been obtained for dimensionless beam spacings, S/L=1~4, aspect ratios of beam, H/B=0.25~4, Reynolds numbers, Re=50~1000 and Grashof numbers, $Gr=0{\sim}5{\times}10^4$. The total mean Nusselt number, Nu_T for horizontal and vertical channels shows same value at Gr=0. As Gr increases, Nu_T for horizontal channel increases, but Nu_T for vertical channel shows similar value at S/L=2, H/B=0.25, Re=100. The total mean Nusselt number for horizontal channel is higher than that for vertical channel. As H/B increases, $Nu_T$ for both channel decrease at $Gr=10^4$, Re=100.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.3
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• pp.183-190
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• 1992

The Collins cryocooler is numerically analysed with the optimization technique, and the optimum operating and design conditions are searched. This paper shows that liquefied helium quantity has an external maximum w.r.t. the total mass flow rate, the mass flow rates through expander and the capacities of heat exchangers. The liquefied helium quantity increases as the compressor exit pressure of the cryocooler does. The maximum quantity of liquefied helium and the maximum coefficient of performance have been found to exist in extremum, depending on the ratios of each heat exchanger capicities to the total one. At the optimum condition, the capacity of heat exchanger in high temperature region is larger than that in low temperature region.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.9
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• pp.671-678
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• 2012

The objective of this study is to analyze theoretically the performance of an open air-cycle refrigeration system in which environmental concerns increase. The pressure ratio of the external compressor and efficiencies of the components that compose of the system are selected as important parameters. As the pressure ratio of the external compressor increases, the pressure ratio of the ACM compressor is determined high, the refrigerating temperature and capacity increase, the COP decreases, and the total entropy production rate increases. The effect of heat exchanger effectiveness and turbine efficiency on the performance are greater than that of the ACM compressor efficiency. Also the performance of the air-cycle refrigeration system with two heat exchangers has been enhanced like high COP and low total entropy production rate, compared to the system with one heat exchanger.

• Journal of Hydrogen and New Energy
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• v.13 no.4
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• pp.304-312
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• 2002

In this study, the performance of the $5Nm^3/hr$ compact type steam reformer which was developed for application of fuel cell or hydrogen station was evaluated in terms of gas process efficiency. For these purposes, reforming efficiency and total efficiency with system load change were analyzed. The reforming efficiency was calculated from the total molar flow of hydrogen output over total fuel flow input to the reformer and the burner on the higher heating value(HHV). In the case of the total efficiency, recovered heat at the heat recovery exchanger was considered. From the results, it was known that system performance was stable, because methane conversion showed the a slight decline which is about 2% though increasing system load to full. Reforming efficiency was increased from 20% to 58%, respectively as increasing system load from 10% to 90%. It was found that total efficiency was higher then reforming efficiency because of terms of heat recovered. As a results, it was known that total efficiency was increased form 75% to 83% at the 10% and 90% system load, respectively. From these results, it is concluded that compact steam reformer which is composed of stacking plate-type reactors is suitable to on-site hydrogen generator or to fuel cell application because of quick start within 1 hr and good performance.

• Korean journal of food and cookery science
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• v.6 no.2
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• pp.85-96
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• 1990

Globefish, Fugu xanthopterus, known to have a severe toxin, is one of the favorite food in Korea and Japan when the toxic part is removed. In this paper, the effect of cooking on the composition of nitrogenous components in the extractives from globefish cooked investigated and the changes of the taste compounds originated from the nitrogenous components in the extractives were discussed. When the sample fish was analysed for general composition, drip amount and pH by the different methods of thawing, the method effective method was the running water thawing. Total nitrogen content in raw globefish and the frozen globefish was not different, and the nitrogen content was increased with the heat treatment. It seemed that the nitrogen content was higher in the extract from the boiled globefish than that of the steamed globefish. Taurine, lysine, glycine and alanine were occupied about 70% of the total free amino acids. Total free amino acid content was higher in the extracts from the frozen sample than those from the raw sample. The amount of free amino acids was increased when the globefish soup cooked under the direct-heat cooking than in the microwave oven-heat cooking. Among nucleotides in the extracts from the thawed and cooked fishes, IMP and inosine contents were increased, and the both components were decreased with the heating time and by the heating method. Tne content of total creatinine-nitrogen were 50% of the total nitrogen content of the extracts, but the concentration of glycinebetaine, TMA and TMAO were only a few amounts. It could be concluded that total creatinine components, including free amino acids such as taurine, lysine, glycine and alanine, and IMP might be the important components contributing to the taste of the cooked globefish.

• 한국해양학회지
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• v.11 no.2
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• pp.43-50
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• 1976

The annual nariation of surface heat exchange at ten selected station in the Korean coastal seas was studied using data of monthly mean surface temperature and meteorological parameters averaged for many years. Through heat exchange between the sea and the atmosphere, the surfaces in the Korean coastal seas are warmed by accepting heat from the atmosphere during march to September in the west coast sea, during Aprill to August in the south coast sea which includes the Ulleung-do coast sea and during April to September in the east coast sea. The periods which are cooled by losing heat to the atmosphere correspond to residual months excepting the above warming periods. Maximum total heat exchange during the warming period at each station shows the distribution of 320-720cal/ $\textrm{cm}^2$ day in June to July and during the cooling period shows the distribution of -260∼-940 cal/$\textrm{cm}^2$ day in November to January. The annual average total heat exchange shows warming of 100-240 Cal/$\textrm{cm}^2$ day in the west coast sea, cooling of -90∼-150 Cal/$\textrm{cm}^2$ day in the south coast sea and the Ulleung-do coast sea, and slight warming or cooling of -15∼65 Cal/$\textrm{cm}^2$ day in the east coast sea. Maxima or minima of the surface temperature in the Korean coastal seas appear in the month that the warming or cooling period is ended. The evaporation rate is highest during October to next January with the distribution of 5∼12mm/day.

• Safety and Health at Work
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• v.14 no.2
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• pp.215-221
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• 2023

Background: There is little information about the airborne hazardous agents released during the heat treatment when manufacturing a welding material. This study aimed to evaluate the airborne hazardous agents generated at welding material manufacturing sites through area sampling. Methods: concentration of airborne particles was measured using a scanning mobility particle sizer and optical particle sizer. Total suspended particles (TSP) and respirable dust samples were collected on polyvinyl chloride filters and weighed to measure the mass concentrations. Volatile organic compounds and heavy metals were analyzed using a gas chromatography mass spectrometer and inductively coupled plasma mass spectrometer, respectively. Results: The average mass concentration of TSP was 683.1±677.4 ㎍/m³, with respirable dust accounting for 38.6% of the TSP. The average concentration of the airborne particles less than 10 ㎛ in diameter was 11.2-22.8×10⁴ particles/cm³, and the average number of the particles with a diameter of 10-100 nm was approximately 78-86% of the total measured particles (<10 ㎛). In the case of volatile organic compounds, the heat treatment process concentration was significantly higher (p < 0.05) during combustion than during cooling. The airborne heavy metal concentrations differed depending on the materials used for heat treatment. The content of heavy metals in the airborne particles was approximately 32.6%. Conclusions: Nanoparticle exposure increased as the number of particles in the air around the heat treatment process increases, and the ratio of heavy metals in dust generated after the heat treatment process is high, which may adversely affect workers' health.