• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.329-332
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• 1999

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as underground box structure, mat-slab of nuclear reactor buildings, dams or large footings, foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, pre-cooling which lowers the initial temperature of fresh concrete with ice flake, pipe cooling which cools the temperature of concrete with flowing water, design change which considers steel bar reinforcement, operation control and so on. The objective of this paper is largely two folded. Firstly we introduce the cracks control technique by employing low-heat cement mix and thermal stress analysis. Secondly it show the application condition of the cracks control technique like sidewall of LNG in Inchonl.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.293-298
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• 1999

The crack of concrete induced by the heat of hydration is a serious problem, particularly in concrete structures such as underground box structure, mat-slab of nuclear reactor buildings, dams or large footings, foundations of high rise buildings, etc.. As a result of the temperature rise and restriction condition of foundation, the thermal stress which may induce the cracks can occur. Therefore the various techniques of the thermal stress control in massive concrete have been widely used. One of them is prediction of the thermal stress, besides low-heat cement which mitigates the temperature rise, pre-cooling which lowers the initial temperature of fresh concrete with ice flake, pipe cooling which cools the temperature of concrete with flowing water, design change which considers steel bar reinforcement, operation control and so on. The objective of this paper is largely two folded. Firstly we introduce the cracks control technique by employing low-heat cement mix and thermal stress analysis. Secondly it show the application condition of the cracks control technique like the subway structure in Seoul.

• The Korean Journal of Malacology
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• v.27 no.4
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• pp.317-322
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• 2011

This study was performed to obtain the basic data on physiological responses of low water temperature stress of the cultured Pacific abalone, Haliotis discus hannai. Abalones were exposed at low water temperatures of $7^{\circ}C$ and $4^{\circ}C$. We have investigated survival rate, superoxide dismutase (SOD) activity and total protein (TP) in the abalone by the exposure times (0, 3, 6, 12, 24, 72, 120, 168 and 216 hours). Survival rate of the abalone at $7^{\circ}C$ experiment was 90.8%, whereas at $4^{\circ}C$ experiment was 0% after exposure 10 days. SOD activity was significantly increased until 12 hours after exposure to $4^{\circ}C$, and then was recovered to starting level after 24 hours. However, there was no significant difference between control ($12^{\circ}C$) and $7^{\circ}C$ experiments. TP was significantly increased until 216 hours after 24 hours at $4^{\circ}C$ experiment, but $7^{\circ}C$ experiment showed no significant differences compared to control ($12^{\circ}C$) experiment. Therefore, H. discus hannai was acclimated in low water temperature stress at $7^{\circ}C$, but at $4^{\circ}C$, all abalone died possibly because they exceed the limits of defense ability to too low temperature.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.733-740
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• 2017

'The facilities standards of water supply' issued by the Ministry of Environment in 2004 indicates that expansion joints cannot be used in welding water supply steel pipes. However, their reason is not clear and it is difficult to confirm the stability of the steel pipe for a water supply pipeline. The purpose of this study is to determine whether or not an expansion joint is necessary to improve the stability of water supply in steel pipe through a displacement analysis of the pipework. The test results are as follows. Firstly, it was found that expansion and contraction of the water supply steel pipe (D 2,400 mm) occur repeatedly in 4 cycles per year, and the maximum expansion and contraction amount of the pipe is 13.03 mm in 1.24 km pipelines. Secondly, the thermal stress caused by expansion and contraction of the steel pipe is $13.7{\sim}36.1kgf/cm^2$ according to the burial depth (0~4 m). The main comparison factors to determine the stability of the steel pipe (STWW 400) were the allowable tensile strength and the fatigue limit, which were computed to be $4,100kgf/cm^2$ and $1,840kgf/cm^2$, respectively. Finally, the thermal stress of the steel pipe is very small compared to the allowable tensile stress and fatigue stress. Therefore, thermal stress does not affect the stability of the steel pipe, although the expansion and contraction of the steel pipe occurs by temperature changes. In conclusion, the study demonstrated that expansion joints are not required in water supply steel pipelines.

• Journal of Biosystems Engineering
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• v.42 no.3
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• pp.163-169
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• 2017

Purpose: This study was performed to evaluate the feasibility of using an infrared thermography technique for phenotype analysis of pepper seedlings exposed to a low-temperature environment. Methods: We employed an active thermography technique to evaluate the thermal response of pepper seedlings exposed to low-temperature stress. The temperatures of pepper leaves grown in low-temperature conditions ($5^{\circ}C$, relative humidity [RH] 50%) for four periods (6, 12, 24, and 48 h) were measured in the experimental setting ($23^{\circ}C$, RH 70%) as soon as pepper seedling samples were taken out from the low-temperature environment. We also assessed the visible images of pepper seedling samples that were exposed to low-temperature stress to estimate appearance changes. Results: The greatest appearance change was observed for the low-temperature stressed pepper seedlings that were exposed for 12 h, and the temperature from these pepper seedling leaves was the highest among all samples. In addition, the thermal image of low-temperature stressed pepper seedlings for 6 h exhibited the lowest temperature. Conclusions: We demonstrated that the leaf withering owing to the water deficiency that occurred under low-temperature conditions could induce an increase in temperature in plant leaves using the infrared thermography technique. These results suggested that the time-resolved and averaged thermal signals or temperatures of plants could be significantly associated with the physiological or biochemical characteristics of plants exposed to low-temperature stress.

• Journal of Korean Society on Water Environment
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• v.37 no.5
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• pp.369-380
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• 2021

In this work, we analyzed the effects of drought on the water temperature (WT) of Nakdong river basin major river sections using Standardized Precipitation Index (SPI) and WT data. The analysis was carried out on a seasonal basis. After calculating the optimal time scale of the SPI through the correlation between the SPI and WT data, we used the copula theory to model the joint probability distribution between the WT and SPI on the optimal time scale. During spring and fall, the possibility of environmental drought caused by high WT increased in most of the river sections. Notably, in summer, the possibility of environmental drought caused by high WT increased in all river sections. On the other hand, in winter, the possibility of environmental drought caused by low WT increased in most river sections. From the risk map, which quantified the sensitivity of WT to the risk of environmental drought, the river sections Nakbon C, Namgang E, and Nakbon K showed increased stress in the water ecosystem due to high WT when drought occurred in summer. When drought occurred in winter, an increased water ecosystem stress caused by falling WT was observed in the river sections Gilan A, Yongjeon A, Nakbon F, Hwanggang B, Nakbon I, Nakbon J, Nakbon K, Nakbon L, and Nakbon M. The methodology developed in this study will be used in the future to quantify the effects of drought on water quality as well as WT.

• Korean Journal of Ichthyology
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• v.22 no.1
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• pp.17-24
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• 2010

The present study investigated the expression of glucocorticoid receptor (GR) mRNA as a stress response during salinity changes (35, 10, and 0 psu) and water temperature changes (from $20^{\circ}C$ to $30^{\circ}C$, $1^{\circ}C$/day) in black porgy. We cloned the full-length GR cDNA from the kidney and examined its expression in the gill, kidney, and intestine by quantitative real-time PCR (QPCR) during salinity and water temperature changes. During salinity changes, the levels of GR mRNA in the gill, kidney, and intestine were highest at 0 psu, and the levels of plasma cortisol and glucose were elevated, but triiodothyronine ($T_3$) decreased. Also, during water temperature changes, the levels of GR mRNA in the gill, kidney, and intestine increased at $30^{\circ}C$. Plasma parameters also increased with an increase in water temperature. Therefore, this upregulation of GR mRNA was a good indicator of stress, such as those resulting from changes in salinity and water temperature.

• BMB Reports
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• v.41 no.5
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• pp.382-387
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• 2008

It is known that the stable protein 1 (SP1) detected in aspen plants remains soluble upon boiling and that sp1 expression in transgenic aspen is resistant to salt stress. Presently, we analyzed the effect of expression of SP1 in Arabidopsis thaliana plants and their response to high temperature stress. After $45^{\circ}C$ for 16 h, relative to wild type plants, sp1 transgenic plants exhibited stronger growth and were better in several physiological properties including chlorophyII, chlorophyII fluorescence, water content, proline content, and malondialdehyde content. These preliminarily results suggest that the over-expression of SP1 may notably enhance heat-tolerant level of transgenic A. thaliana plants.

• Journal of Marine Life Science
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• v.2 no.1
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• pp.34-38
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• 2017

FK506BP (FK506 binding protein 12) is a small peptide with a single FK506BP domain. It is involved in suppression of immune response, oxidative stress and inflammation. The purpose of this study was to investigate the gene expression of FK506BP in red seabream (Pagrus major) exposure to low water temperature (8℃, 33 psu) and low salinity (20℃, 10 psu). Results showed that, the expression of FK506BP was significantly increased in the experiment groups, such as low water temperature (8℃, 33 psu), and low salinity (20℃, 10 psu). These results suggest that FK506BP was played roles in biomarker gene on the environmental stress such as water temperature and salinity.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.70.2-70
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• 2002

In the thermal power plant, it is difficult to maintain strict control of the steam temperature in order to avoid thermal stress, because of variation of the heating value according to the fuel source, the time delay of changes in main steam temperature versus changes in fuel flow rate, difficulty of control on the main steam temperature control and the reheater steam temperature control system owing to the dynamic response characteristics of changes in steam temperature and the reheater steam temperature, fluctuation of inner fluid water and steam flow rates widely during load-following operation. Up to the present time, the PID controller has been used to operate this system...