• Steel and Composite Structures
• /
• v.32 no.5
• /
• pp.687-699
• /
• 2019

In this paper, free and force vibration behaviors of graphene-reinforced composite functionally graded (GRC-FG) cylindrical shells in thermal environments are investigated based on Reddy's third-order shear deformation theory (HSDT). The GRC-FG cylindrical shells are composed of piece-wise pattern graphene-reinforced layers which have different volume fraction. Based on the extended Halpin-Tsai micromechanical model, the effective material properties of the resulting nanocomposites are evaluated. Using the Hamilton's principle and the assumed mode method, the motion equation of the GRC-FG cylindrical shells is formulated. Using the time- and frequency-domain methods, free and force vibration properties of the GRC-FG cylindrical shell are analyzed. Numerical cases are provided to study the effects of distribution of graphene, shell radius-to-thickness ratio and temperature changes on the free and force vibration responses of GRC-FG cylindrical shells.

• Journal of the Korean Society for Geothermal and Hydrothermal Energy
• /
• v.16 no.4
• /
• pp.16-23
• /
• 2020

In this study, the control characteristics and effects of control methods on heating performance and energy consumption for the hot water floor radiant heating control system of a residential apartment were research by experiment. As a control method, On-Off control and outdoor reset control methods with GRNN(General Regression Neural Network) and without GRNN are considered. Also, the control performances with regard to improvement of indoor thermal environment and reduction of energy consumption are compared, respectively. Experiment results show that the performance of the control method with GRNN is better than that of conventional on-off control method without GRNN in the responses of room set temperature and energy saving.

• Steel and Composite Structures
• /
• v.42 no.5
• /
• pp.649-655
• /
• 2022

In presented paper, moving load problem of simply supported axially functionally graded (AFG) beam is investigated under temperature rising based on the first shear beam theory. The material properties of beam vary along the axial direction. Material properties of the beam are considered as temperature-dependent. The governing equations of problem are derived by using the Lagrange procedure. In the solution of the problem the Ritz method is used and algebraic polynomials are used with the trivial functions for the Ritz method. In the solution of the moving load problem, the Newmark average acceleration method is used in the time history. In the numerical examples, the effects of material graduation, temperature rising and velocity of moving load on the dynamic responses ofAFG beam are presented and discussed.

• Nuclear Engineering and Technology
• /
• v.49 no.1
• /
• pp.54-70
• /
• 2017

The accumulator is a passive safety injection device for emergency core cooling systems. As an important safety feature for providing a high-speed injection flow to the core by compressed nitrogen gas pressure during a loss-of-coolant accident (LOCA), the accumulator injects its precharged nitrogen into the system after its coolant has been emptied. Attention has been drawn to the possible negative effects caused by such a nitrogen injection in passive safety nuclear power plants. Although some experimental work on the nitrogen injection has been done, there have been no comparative tests in which the effects on the system responses and the core safety have been clearly assessed. In this study, a new thermal hydraulic integral test facility-the advanced core-cooling mechanism experiment (ACME)-was designed and constructed to support the CAP1400 safety review. The ACME test facility was used to study the nitrogen injection effects on the system responses to the small break loss-of-coolant accident LOCA (SBLOCA) transient. Two comparison test groups-a 2-inch cold leg break and a double-ended direct-vessel-injection (DEDVI) line break-were conducted. Each group consists of a nitrogen injection test and a nitrogen isolation comparison test with the same break conditions. To assess the nitrogen injection effects, the experimental data that are representative of the system responses and the core safety were compared and analyzed. The results of the comparison show that the effects of nitrogen injection on system responses and core safety are significantly different between the 2-inch and DEDVI breaks. The mechanisms of the different effects on the transient were also investigated. The amount of nitrogen injected, along with its heat absorption, was likewise evaluated in order to assess its effect on the system depressurization process. The results of the comparison and analyses in this study are important for recognizing and understanding the potential negative effects on the passive core cooling performance caused by nitrogen injection during the SBLOCA transient.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.15 no.2 s.38
• /
• pp.77-87
• /
• 1991

The purpose of this study were to investigate the bed climate and the physiological responses in sleep on the traditional Korean floor heating system called Ondol. Ondol has been the most widely used heating system in Korea, yet there has been a no systematic studies examined its environmental effects on human body. Experimental room was constructed to match the typical thermal environment of Ondol. (floor surface temperature; $32\~33^{\circ}C$, air temperature; $22.5{\pm}1.0^{\circ}C$, relative humidity; $64.0{\pm}4.0\%$RH, air velocity; 0.25 m/sec.) Three different combinations of bedclothes were chosen for the experiment based on the study results showing that they were the most widely used types in Korea. Type 1 was the combination of a cotton-padded mattress with a cotton-padded Korean style blanket. Type 2 was a cotton-padded mattress with a cotton-guilted Korean style blanket. Type 3 was a cotton-padded matless with a polyacryl blanket. Thermal resistance of each of these combina-tions in the bedclothes was measured using thermal manikin. Two adult female was chosen for the seven hour sleeping experiment which was known to be the average sleeping hours of Korean adult female. The bed climate was measured with the temperature under the mattress, the surface temper-ature of the mattress, and the air temperature and the relative humidity of the space between the mattress and blanket. The skin temperature, rectal temperature of the subjects and the bed climate were measured eight times, one hour before the experiment and every hour during the experiment. The weight loss and the subjective sensation were measured for the each subjects before and after the experiment. The procedure was repeated twice with two subjects and three types of bedclothes, yielding twelve combinations of results. The results were as follows; 1. With the surface temperature of $32\~33^{\circ}C$ of Ondol, air temperature was $22.5{\pm}1.0^{\circ}C$ with $64.0{\pm}4.0\%$ RH. The bed climates were $39.2{\pm}40.8^{\circ}C$ under the mattress, $35.3\~36.2^{\circ}C$ on the mattress, and $26.9\~32.0^{\circ}C$ with $56.0\~71.3\%$ RH between the mattress and the blanket. 2. Mean skim temperature during sleep was 34.2"C with local skin temperature of $34.0\~35.5^{\circ}C$. The skin temperatures of abdomen, thigh, foot were higher than the other parts of the body. 3. The skin temperature of chest, thigh, leg and back varied significantly according to the combinations of bedclothes. With the cotton-padded blanket, the skin temperature was the highest, while with the cotton-guilted blanket showed lowest. 4. Examining the relationship between the mean skin temperature and the local skin temper-ature, the chest temperature showed the highest correlation with the former. Therefore, the chest temperature can be recommended to represent the skin temperature in measuring the bed climate. 5. The subjective bed climates were $39.0\~40.4^{\circ}C$ under the mattress, $35.2\~35.9^{\circ}C$ on the mattress, $29.8\~31.6^{\circ}C$ with $56.8\~68.4\%$ RH between the mattress and blanket. In sum, from this experiment we not only obtained the reliable value of bed climates on Ondol, but also showed that the bed climates and the physiological responses were affected differently according to the materials of bed clothes.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.30 no.3
• /
• pp.223-228
• /
• 1985

Photosynthetic inhibition to temperature were conducted with ginseng(4 year old) and tobacco(var. Bulgaria). The plants were kept under various temperature conditions from 1$0^{\circ}C$ to 4$0^{\circ}C$ and 440$\mu$E/$m^2$/sec for 3 and 6hrs, and net $CO_2$ uptake were measured after 2hrs at $25^{\circ}C$. Photosynthetic optimal leaf temperature of ginseng was 21$^{\circ}C$ and tobacco was $25^{\circ}C$. Stomatal resistance and mesophyll resistance increased at high temperature. Especially, stomatal resistance seemed to have a significant role in determining the temperature responses of photosynthesis. In tobacco photosynthetic capacity was not changed by temperature treatment for 3hrs. However, 6hrs exposure reduced 8% of net photosynthesis at 4$0^{\circ}C$ and 12% at 1$0^{\circ}C$. Ginseng plants exposed for 6hrs at 4$0^{\circ}C$ lost photosynthetic capacity by 83%. Temperature responses of ginseng were very sensitive at above-optimum temperature resulting greater thermal inhibition other than photoinhibition.

• Korean Journal of Ichthyology
• /
• v.23 no.1
• /
• pp.61-69
• /
• 2011

Gene and promoter structures of metallothionein(MT) from Miho spine loach (Cobitis choii; Cypriniformes) were characterized, and the transcriptional responses to experimental exposures to heavy metals and heat stress were examined. The C. choii metallothionein displayed well-conserved features of teleostean metallothioneins at gDNA, mRNA and amino acid levels. Bioinformatic analysis predicted that the C. choii MT regulatory region potentially possessed various motifs or elements targeted by various transcription factors associated with metal-coordinating regulation (e.g., metal transcription factor-1), immune responses (e.g., nuclear factor kappa B), and thermal modulations (e.g., heat shock factor). Acute heavy-metal exposures to 0.5 or $1.0\;{\mu}M$ of cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni) or zinc (Zn) showed that MT transcription was significantly stimulated by Cd (9.6-fold relative to non-exposed control) and Cu (10.4-fold), only moderately by Mn (2.4-fold), but hardly by Ni and Zn. Elevation of water temperature from $25^{\circ}C$ to $31^{\circ}C$ caused a rapid modulation of MT mRNAs toward upregulation to 9.5-fold; however, afterward the elevated mRNA level slightly decreased during further incubation at $31^{\circ}C$ for 6 h. Results from this study suggest that MT-based expression assay could be a useful basis for better understanding the metal- and/or heat-caused stresses in this endangered fish species.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.20 no.6
• /
• pp.983-991
• /
• 1996

This study focusses on how the skirt or slacks wearing habit affects the female physiology in her daily life. The healthy female college students have been trained to wear either skirt (group A) or slacks (group B) from late August to early January in order to study the effects of clothing habit on thermoregulatory responses. Also, the themoregulatory responses have been compared the healthy students groups with a physical trained students group (group C) to examine the effects of clothing habit. The changes in body temperatures of students have been studied under the cool environmental condition (15$\pm$1$^{\circ}C$, 60$\pm$5% RH, 0.25 m/sec). The results were as follows: 1. Rectal temperature of the group A was 0.4$^{\circ}C$ lower at 36.9$^{\circ}C$ than that of the group B The groups A and B were found identical before the training, while the groups A and C were identical after the training. 2. Mean skin temperature of the group A was 1.2$^{\circ}C$ lower than that of the group B. The groups A and C were identical after the training. 3. The thermal sensation was reflected to be cool by the group A and to be cold by the group B. As for the humidity sensation, the group A felt average, whereas the group B reported between average and slightly humid. In the case of comfort sensation, the group A felt average, while the group B felt between average and slightly uncomfortable. In summary, the 18 weeks of training has provided the skirt group an improved acclimatization to the cold environment . This group also showed an insulative-hypothermic adapta lion in a cold ambient temperature, as was the case for the physical trained group. It is concluded that wearing a skirt for a long period of time can be helpful to human body through gaining of thermoregulatory abilities.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.23 no.4
• /
• pp.499-509
• /
• 1999

This study was carried out to investigate the effects of wearing disposable diaper with the endothermic agent on thermoregulatory response of infant. Five healthy female infants aged about 5 months were taken as a subject of this experiment. Experimental diapers were six kinds of disposable diaper constructed of nonwoven tissue, fluff pulp, super absorbent polymer, back sheet film, leg elastic, and 0g urea(A) 1g urea(B) , 2g urea(C), 3g urea (D), 4g urea(E) 5g, urea(F) respectively. Urea(98% or over purity) was used as an endothermic agent. Experiment was proceeded while infants were sleeping at 27.5$\pm$0.5$^{\circ}C$, 50$\pm$5% R.H, 0.04m/sec. Each disposable diaper's properties was tested. During the experiment rectal temperature skin temperature of 9 areas temperature inside the disposable diapers were measured, the results were as follows : 1) There was not significant difference among the diapers in absorption capacity retention capacity and rewet(p=0.05). The absorption under load was showed to A, B,

• Journal of the Korean Society of Clothing and Textiles
• /
• v.32 no.10
• /
• pp.1651-1658
• /
• 2008

This study was to decided the proper garment pressure level on the human body parts. Six volunteers (female: 30-40years) put on the same types of bands, a brief, and a non-woven gown. Garment pressure was measured in regular order with the elastic band on the human body parts such as the upper arm, the waist, the thigh, and the calf. At the same time, physiological responses such as the skin blood flow rate on 2 fingers, 7 different skin temperatures, rectal temperature, heat rates, and subjective responses about the pressure sensation, thermal sensation, and humidity sensation were measured and inquired. The results were as follows; 1. The thicker subcutaneous fat thickness, the higher the mean garment pressure on pressurizing the upper arm(p<.001). Also the thicker subcutaneous fat thickness. the thicker the upper arm circumference. 2. Heart rates increased pressured the upper arm and decreased pressured the waist, the thigh, and the calf. The higher the garment pressure, the higher heart rates on all body parts were pressured. Especially lean subjects showed higher physiological load than others. 3. On pressurizing the upper arm, heart rates, rectal temperature, and mean skin temperature were higher than without pressured state and pressured other body parts.4. The proper garment pressure levels were decided 30gf/$cm^2$ for fat people, 20gf/$cm^2$ for others on the upper arms and 24gf/$cm^2$ on the calf.