• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.54 no.3
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• pp.262-270
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• 2018

We examined the characteristics of egg and larval distributions and catch changes of anchovy in relation to abnormally high sea temperature in the South Sea of Korea in summer 2015 and 2016. The densities of anchovy eggs and larvae in the southern coastal region were lower in July-August 2016 than in July-August 2015. In particular, anchovy eggs and larvae (approximately 5 mm TL) were rarely observed in the coastal region in August 2016 due to the abnormally high SST (up to $28^{\circ}C$), which was above the optimum spawning temperature of anchovy. The catch of non-swimming stage (< 2 cm TL) larval anchovy was lower in July-August 2016 than in July-August 2015. The decreased catch of larval anchovy in July-August 2016 could be attributed to decreased spawning density in June-July 2016. In contrast, the catch of swimming stage (> 2 cm TL) anchovy was increased in July-August 2016. In the summer of 2016, prominent sea temperature near the southern coast of Korea and sea temperature higher than $30^{\circ}C$ in the offshore region of the South Sea of Korea could greatly enhance the retention of swimming anchovies in the coastal fishing grounds.

• Journal of Korean Society of Rural Planning
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• v.19 no.4
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• pp.115-123
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• 2013

Owing to increase of meteorological disasters by climate change, it needs to study of climate change which will be able to deal with adaption for basic local authorities. A case study area of Yesan have been impacted by land-use which alter natural environment demage. It has led to micro-climate change impacts in rural area, Yesan. In order to adapt to the effects, this paper estimated temperature change in productivity of fruits and conducted decline of nonpoint pollutant loadings. As the results of temperature change of effecting on growth of apple, since a rise in temperature have not increased high, therefore the apple productivity could not be influence until 2030s. While the apple productivity could be declined 14.8% in 2060s. In addition, it supposes that the productivity would be decreased 44.5% in 2090s. Furthermore, it showed that the apple maturity has become worse, because length of high temperature has dramatic increased 54.2% in 2030s, 103.2% in 2060s and 154.0% in 2060s beside 2000, respectively, compared with 2000. As results of analysing between the future rainfall characteristics and nonpoint pollutant loadings, the subject of reduction of nonpoint pollutant was efficiency when it implemented around Oga-myeon or Deoksan-myeon Dun-ri. This study classified the region more detail each Eup and Myeon after that it analysed the rural region impacts of climate change for basic local authorities. Hence, this study is able to predict adaptation of rural region impacts of climate change. Due to increase of green house gases emission, meteorological disasters could often occur in the future. Therefore, it needs follow-up studies that assess climate change of effecting on rural region.

• International Journal of Automotive Technology
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• v.1 no.2
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• pp.71-77
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• 2000

High temperature materials in service are subjected to mechanical damage due to operating load and metallurgical damage due to operating temperature. Therefore, when designing or assessing life of high temperature components, both factors must be considered. In this paper, the effect of tensile hold time on high temperature fatigue crack growth and long term prior thermal aging heat treatment on creep rupture behavior were investigated using STS 316L and STS 316 austenitic stainless steels, which are widely used for high temperature components like in automotive exhaust and piping systems. In high temperature fatigue crack growth tests using STS 316L, as tensile hold time increased, crack growth rate decreased in relatively short tensile hold time region. In long term aged specimens, cavity type microcracks have been observed at the interface of grain boundary and coarsened carbide.

• Journal of the Korean Society for Heat Treatment
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• v.27 no.5
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• pp.235-241
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• 2014

Effects of rolling and cooling conditions on microstructures and mechanical properties of high-deformable pipeline steels were investigated in this study. Six kinds of pipeline steels were fabricated by varying rolling and cooling conditions, and their microstructures were analyzed by scanning electron microscopy, electron back-scattered diffraction, and transmission electron microscopy. Tensile and Charpy impact tests were conducted on the steels in order to examine the mechanical properties. The steels rolled in the two-phase region showed better low-temperature toughness than those in the single-phase region due to the larger amount of ferrites having high-angle boundaries, although they have lower strength and absorbed energy. The steel rolled in single-phase and finish-cooled at higher temperature showed a good combination of high strength and good low-temperature toughness as well as excellent deformability of the lowest yield ratio and the highest uniform elongation because of the presence of fine ferrite and a mixture of various low-temperature transformation phases.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.183-190
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• 2002

In order to reduce NOx emissions in the 20kw class microturbines under development, the low NOx characteristics, as being an application to the lean premixed combustion technology, have been investigated. The study has been conducted at the conditions of high temperature and pressure. Air from a compressor with the temperature of 500K to 650K and the pressure of 0.3bar gauge to 0.7bar gauge, was supplied to the combustor through an air preheat-treatment. Sampling exhaust gases were measured at the immediate exit of the combustor. for the effect of temperature on NO and CO emissions. though NOx was increased, CO was decreased with increasing inlet air temperature. With increasing inlet air pressure, NOx and CO were increased also. NOx was decreased, but CO was increased with increasing inlet air mass flow rate. The test has been performed on the equivalent ratios of 0.10 to 0.25 in a lean region. NOx was increased with increasing equivalent ratios, but CO was decreased as an influence of flame temperature. In the very lean region of the equivalent ratio below 0.12, CO was increased suddenly, due to instability. As the results of this study, NOx and CO are found to be reduced to the similar level at the same time when operated at optimal conditions.

• Journal of the Korean Geographical Society
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• v.49 no.1
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• pp.32-44
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• 2014

This study aimed to analyze the characteristic of the distribution of minimum temperature during January in the central region of South Korea and to investigate causes for the occurrence of extreme minimum temperature in Cheorwon. January temperature distribution data which were collected from 25 weather stations in central area from 1991 to 2010 were investigated, and the difference of temperature between Cheorwon and the other stations in central region, such as Chuncheon, Hongcheon, Bonghwa, Daegwallyoung, Wonju and Jecheon were analyzed by the type of atmospheric pressure system. Daily mean temperature and mean of daily minimum temperature appear to be low at Cheorwon and at the sites in high altitudes, but the frequency of extreme cold wave such as below $-15^{\circ}C$ is also noticeable in Cheorwon. When the Siberian High has expanded and migratory anticyclone has moved onto the north of the Korean Peninsula, the temperature at Cheorwon is relatively low. Furthermore it shows a lesser difference between Cheorwon and the compared stations when the migratory anticyclone affected the area, even at basin like Bonghwa, Jecheon more lower than Cheorwon.

• Nuclear Engineering and Technology
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• v.56 no.3
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• pp.785-792
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• 2024

This article provides an overview of the design methodology used to develop a conceptual set of reactivity control mechanism of a micro reactor based on the U-Battery. The U-Battery is based on remote deployment and therefore it is favourable to provide a long fuel lifecycle. This is achieved by implementing a high fissile loading content, which proves challenging when considering reactivity control methods. This article follows the design methodology used to overcome these issues, with an emphasis on a new concept of a moveable moderator which utilises the size of the U-Battery as a small reduction in moderation provides a significant reduction in reactivity. The latest work on this project sees the moveable moderator investigated during a depressurised loss of forced coolant accident, where a reduction of moderator volume increases the maximum fuel temperature experienced. The overall conclusion is that the maximum fuel temperature is not significantly increased (4 K) due to the central reflector region relatively lower volumetric heat capacity compared to that of whole core. However, a small temperature increase is observed immediately after the transient due to the central reflector removal because it reaches energy equilibrium with the fuel region faster.

• Transactions on Electrical and Electronic Materials
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• v.17 no.2
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• pp.104-108
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• 2016

To research the correlation between oxygen vacancy and the electrical characteristics of ZTO, which is made by using a target mixed ZnO:SnO₂=1:1, the ZnO, SnO₂ and ZTO were analyzed by PL, XPS, XRD patterns and electrical properties. It was compared with the electron orbital spectra of O 1s in accordance with the electrical characteristics of ZnO, SnO₂ and ZTO. The electrical characteristics of ZTO were improved by increasing the annealing temperatures, due to the high degree of crystal structures at a high temperature, and the physical properties of ZTO was similar to that of ZnO. The amorphous structure of SnO₂ was increased with increasing the temperature. The Schottky contact of oxide semiconductors was formed using the depletion region, which is increased by the electron-hole combination due to the annealing processes. ZnO showed the Ohmic contact in spite of a high annealing temperature, but SnO₂ and ZTO had Schottky contact. As such, it was confirmed that the electrical properties of ZTO are affected by the molecules of SnO₂.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.7 s.178
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• pp.1673-1680
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• 2000

The degradation of a boiler header constructed by a material, 1Cr-0.5Mo steel in a fossil power plant is observed when the header is exposed for a long period to the high temperature and pressure. The present investigations are for evaluating the effect of the degradation on the material, such as its strength changes. Reheat-treated metal is used to compare the mechanical properties of the degraded and that of reheat-treated materials. Through the investigation, following results are obtained 1) the area ratio of ferrite in the reheat-treated material is larger than that of the degraded material, 2) the hardness and tensile strength of the degraded material are lower than that of the reheat-treated material, 3) the ductile-brittle transition temperature(DBTT) increased toward high temperature region, 4) the fatigue crack growth rate(FCGR) of the degraded material is higher than that of the reheat-treated material in the region of low ΔK value while FCGR of the both materials are similar in high ΔK region.

• Applied Chemistry for Engineering
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• v.29 no.1
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• pp.103-111
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• 2018

A plasma-catalytic combined process was used as an attempt to improve the conversion efficiency of nitrogen oxides ($NO_x$) over a wide temperature range ($150{\sim}500^{\circ}C$) to cope with the exhaust gas whose temperature varies greatly. Since the catalytic $NO_x$ reduction is effective at high temperatures where the activity of the catalyst itself is high, the $NO_x$ reduction was carried out without plasma generation in the high temperature region. On the other hand, in the low temperature region, the plasma was created in the catalyst bed to make up for the decreased catalytic activity, thereby increasing the $NO_x$ conversion efficiency. Effects of the types of catalysts, the reaction temperature, the concentration of the reducing agent (n-heptane), and the energy density on $NO_x$ conversion efficiency were examined. As a result of comparative analysis of various catalysts, the catalytic $NO_x$ conversion efficiency in the high temperature region was the highest in the case of the $Ag-Zn/{\gamma}-Al_2O_3$ catalyst of more than 90%. In the low temperature region, $NO_x$ was hardly removed by the hydrocarbon selective reduction process, but when the plasma was generated in the catalyst bed, the $NO_x$ conversion sharply increased to about 90%. The $NO_x$ conversion can be maintained high at temperatures of $150{\sim}500^{\circ}C$ by the combination of plasma in accordance with the temperature change of the exhaust gas.