• Proceedings of the Korean Society of Crop Science Conference
• /
• 2022.10a
• /
• pp.265-265
• /
• 2022

Increased temperature caused by global warming has become a significant problem for the growth and production of crops. A high temperature has a direct or an indirect effect on crops, leading to a significant yield loss. The damage of a high temperature stress to rice depends on its developmental stage. In present study, we performed evaluate the heading date in different location, Yeoju and Miryang, during growth of Korean rice core set. The heading date for the 223 rice accession were evaluated in Yeoju City (37°23' 127°57') and Miryang City (35°50', 128°72') located on middle and southern part of Korea, respectively. The average temperature of a day was higher in Miryang during entire growth stage. Here, total 222 KRICE-Core set was analyzed by GWAS for the high temperature effect. GWAS results revealed the Chr07_26954556, a lead SNPs were significantly associated with delaying heading date of KRICE-Core set. Significance threshold was set with 6.0 > -log10(P), and Cross-Validation (CV) error suggested an optimal K value of 5 for the population based on the lowest cross-validation error K = 5.

• Journal of the Korean Ceramic Society
• /
• v.46 no.2
• /
• pp.131-136
• /
• 2009

Radio frequency (RF) plasma treatment is studied for the size reduction and the spheroidization of coarse particles to change them into nano-sized powders of spherical shape in MLCC fields. The uni-nanoadditives manufactured by RF plasma processing for high dispersion have been investigated for the effect on core-shell structure in dielectrics of MLCC. Microstructures have been characterized using scanning electron microscope (SEM), transmission electron microscope (TEM) and Electron Probe Micro Analyzer (EPMA). We compared the distribution of core-shell grains between specimens manufactured using uni-nanoadditive and using mixed additive. In addition, the uniformity of rare earth elements in the core-shell structured grains was analyzed. It was shown, from TEM observations, that the sintered specimen manufactured using uni-nanoadditives had more dense small grains with well-developed core-shell structure than the specimen using mixed additives, which had a homogeneous microstructure without abnormal grain growth and shows broad temperature coefficient of capacitance (TCC) curves in all temperature ranges because of well dispersed additives.

• Nuclear Engineering and Technology
• /
• v.48 no.2
• /
• pp.318-329
• /
• 2016

Reducing critical boron concentration in a commercial pressurized water reactor core offers many advantages in view of safety and economics. This paper presents a preliminary investigation of a reduced-boron pressurized water reactor core to achieve a clearly negative moderator temperature coefficient at hot zero power using the newly-proposed "Burnable absorber-Integrated Guide Thimble" (BigT) absorbers. The reference core is based on a commercial OPR1000 equilibrium configuration. The reduced-boron ORP1000 configuration was determined by simply replacing commercial gadolinia-based burnable absorbers with the optimized BigT-loaded design. The equilibrium cores in this study were directly searched via repetitive Monte Carlo depletion calculations until convergence. The results demonstrate that, with the same fuel management scheme as in the reference core, application of the BigT absorbers can effectively reduce the critical boron concentration at the beginning of cycle by about 65 ppm. More crucially, the analyses indicate promising potential of the reduced-boron OPR1000 core with the BigT absorbers, as its moderator temperature coefficient at the beginning of cycle is clearly more negative and all other vital neutronic parameters are within practical safety limits. All simulations were completed using the Monte Carlo Serpent code with the ENDF/B-VII.0 library.

• Journal of the Korean Society of Safety
• /
• v.14 no.4
• /
• pp.78-84
• /
• 1999

A compact air-preheating type heat exchanger was developed and tested for the ultra-high temperature heat recovery applications. For the direct use of exhaust gases up to $1200^{\circ}C$, the heat exchanger adopted a ceramic core with high strength and low thermal expansion coefficient less than $1{\times}10^{-6}^{\circ}C^{-1}$. The ceramic core was fabricated by special extrusion and bonding techniques. To minimize thermal stresses in the core, spring-loaded sealing mechanism was designed and successfully installed. 1-pass air flow scheme was adopted for the compactness and cost-savings. The pressure test for the ceramic core showed no failure under 35 kPa and less than 3% leak under 7 kPa. Flue gas simulation system was developed to investigate the performance of the heat exchanger. The test results showed normal operations of the heat exchanger up to $1200^{\circ}C$ of exhaust gases and relatively high heat recovery efficiencies of 31～39% depending upon exhaust gas temperatures..

• Proceedings of the Korean Nuclear Society Conference
• /
• 1996.05b
• /
• pp.598-603
• /
• 1996

When locked rotor event. occurs, instantaneously affected loop and core flow were quickly reduced, which resulted in an increase in coolant temperature and system pressure. Analysis method of this event was that constant core inlet temperature and system pressure as well as change in core flow calculated from COAST code were statically used as an input variable to HERMITE code, because of no tools to simulate NSSS behavior and 1-D core neutronics transient coincidently. With employing TASS code revised with 1-D neutronics model, this event was analyzed in point of DNBR. By doing so, analysis procedure could be simplified and unreasonable conservatism might be removed in DNBR calculation by consideration of pressure increase.

• Journal of the Korean Society of Safety
• /
• v.11 no.4
• /
• pp.107-114
• /
• 1996

A study to Improve the safety of the ceramic heat exchanger In the high temperature heat recovery system was performed in terms of air flow passes. The numerical and finite element analyses on the heat transfer and thermal stresses in the ceramic core related with air passes were carried out. The results showed that the stresses in the ceramic core induced by the thermal expansion are large enough to cause failure of the brittle ceramic core. The imployment of triple-pass air flow for the same ceramic core could increase the efficiency and effectively release approximately 20% of the maximum thermal stressess, thus improving the safety of the ceramic heat exchanger. The use of triple-pass, however, is limited by the amount of air flow due to the increase of pressure drop.

• Nuclear Engineering and Technology
• /
• v.52 no.12
• /
• pp.2699-2708
• /
• 2020

Helical-coil steam generator (HCSG) technology is a major design candidate for small modular reactors due to its compactness and capability to produce superheated steam with high generation efficiency. In this paper, we investigate the feasibility of the passively autonomous power maneuvering by coupling the 3-D transient multi-physics of a soluble-boron-free (SBF) core with a time-dependent HCSG model. The predictor corrector quasi-static method was used to reduce the cost of the transient 3-D neutronic solution. In the numerical system simulations, the feedwater flow rate to the secondary of the HCSGs is adjusted to extract the demanded power from the primary loop. This varies the coolant temperature at the inlet of the SBF core, which governs the passively autonomous power maneuvering due to the strongly negative coolant reactivity feedback. Here, we simulate a 100-50-100 load-follow operation with a 5%/minute power ramping speed to investigate the feasibility of the passively autonomous load-follow in a 450 MW_th SBF PWR. In addition, the passively autonomous frequency control operation is investigated. The various system models are coupled, and they are solved by an in-house Fortran-95 code. The results of this work demonstrate constant steam temperature in the secondary side and limited variation of the primary coolant temperature. Meanwhile, the variations of the core axial shape index and the core power peaking are sufficiently small.

• Journal of Nutrition and Health
• /
• v.31 no.7
• /
• pp.1130-1138
• /
• 1998

The objective of this study was to investigate the relationship between changes in body temperature, adiposity and sympathoadrenal activity in normal weight female college students, eating an instant-noodle lunch in a laboratory setting at ambient temperatures of 22-24.8$^{\circ}C$. Preprandial epinephrine(EPI) concentration, as an indicator of adrenal activity, was inversely and significantly correlated with body weight, body mass index(BMI), and waist girth. Changes in pre- and postprandial EPI concentrations showed positive correlations with % body fat, fat mass, waist girth, hip girth, and waist/hip girth ratio(WHR). The preprandial norepinephrine (NE) concentration was negatively correlated with recovery time from the peak postprandial core temperature to the meal-start core temperature(RTST). However, the NE concentration, an indicator of sympathetic neural activity, was not related to anthropometric measurements in normal weight young women. In conclusion, adrenal activity was negatively associated with adiposity and central body fat distribution. Sympathetic activity was related to body temperature regulation capacity after a meal, but was not related to adiposity in normal weight young women. (Korean J Nutrition 31(7) 1130-1138, 1998)

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
• /
• v.25 no.4
• /
• pp.35-44
• /
• 2012

Objectives : This study was aimed to evaluate the treatment effect of psoriasis patient using pyretotherapy. Methods : The clinical study was performed using retrospective observational research method. Treatment method was pyretotherapy that optimized core temperature through herbs therapy, food therapy, excercise and life style change. In other aspects, pyretotherapy is skin cure therapy that rise core temperature, down skin temperature and open sweat gland. Results : 1. 40s years showed the most coming of clinic in the distribution of age of psoriasis patient. 2. Board type showed the most number in the classification of psoriasis. 3. Pyretotherapy was very effective results in psoriasis patient treatment. 4. Pyretotherapy showed effects of rising axillary temperature and moving facial high skin temperature toward abdominal portion. Conclusions : The author is able to say that it is possible for pyretotherapy to become new skin therapy for many skin disease, especially psoriasis.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.12
• /
• pp.2279-2282
• /
• 2007

Highly crystalline, uniform Fe nanoparticles were successfully synthesized and encapsulated in zirconia shell using sol-gel process. Two different approaches have been employed for the coating of Fe nanoparticle with zirconia. The thickness of zirconia shell can be readily controlled by altering molar ratio of Fe nanoparticle core to zirconia precursor in the first case where as reaction time was found to be most effective parameter to controlled the shell thickness in the second method. The structure and magnetic properties of the ZrO2-coated Fe nanoparticles were studied. TEM and HRTEM images show a typical core/shell structure in which spherical α-iron crystal sized of ~25 nm is surrounded by amorphous ZrO2 coating layer. TGA study showed an evidence of weight loss of less than 2% over the temperature range of 50-500 °C. The nanoparticles are basically in ferromagnetic state and their magnetic properties depend strongly on annealing temperature. The thermal treatment carried out in as-prepared sample resulted in reduction of coercivity and an increase in saturation magnetization. X-ray diffraction experiments on the samples after annealing at 400-600 °C indicate that the size of the Fe@ZrO2 particles is increased slightly with increasing annealing temperature, indicating the ZrO2 coating layer is effective to interrupt growing of iron particle according to heat treatment.