• 한국해양학회지
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• 제19권1호
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• pp.11-17
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• 1984

1981년 7월 7일~12일 기간중 동해에서의 해양관측 결과와 국립수산진흥원 (1961~1981년) 및 일본 기상청 자료(1975, 1981년)를 분석한 결과, 1981년 하계의 1$0^{\circ}C$ 등온선이 130 E선의 35 30 N 이남 해역에서 약 75m 이심에 나타났으나 이 이북 해역에서부터 20~30m로 급격히 상승했다. 한편, 1966~1981년의 130 E선 에서 35 N~37 30 N의 3정점의 깊이 100m의 수온표준편차는 2~4$^{\circ}C$로서 변동폭이 매우 컸다. 1981년 하계의 수온 편차는 표준 편자의 1.5배 이상이며, 수심 150m 이천은 평년에 비해 5~1$0^{\circ}C$ 낮았다. 특히 1$0^{\circ}C$ 등온선이 평년보다 20~120마일 남하하여 35 N~36 N 해역에 까지 이르렀다. 이상의 결과를 종합해 볼 때 1981년은 약 15년 (1966~1981년) 동안에 처음 있는 이상 저수온년이었다.

• 한국해양학회지
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• 제19권2호
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• pp.125-132
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• 1984

동계의 이상저온이 하계에 발생하는 황해저층냉수의 이상저온 현상에 미치는 영향을 규명하기 위해서 1981년 7월에 실시한 해양 관측 결과와 기상 자료 (1960~1981년) 및 국립수산진흥원 발행의 해양조사년보(1960~1981년)를 사용하여 검토하였다. 하계 황해저층에서 발생하는 이상저온현상은 전년 동계의 이상기상 현상과 밀접한 연구가 있음을 알 수 있다. 즉 1980년의 동계는 기온이 평년에 비해 1~8$^{\circ}C$ 낮았으며, 북서 계절풍도 강하여 황해냉수가 이상적으로 발달 하였고, 또 표면수온도 1~3$^{\circ}C$ 낮았다. 이때 발생한 냉수의 영향으로 1981년 하계의 저층냉수는 평년보다 2~3$^{\circ}C$ 이상 낮은 저온현상을 보였고, 그 범위도 서해연안과 제주도 서방 약 50마일 해역까지 확장하였다. 평년에 비해 1981년 2월의 깊이 30m의 수온이 소흑산도 부근을 제외한 전해역에서는 1~2$^{\circ}C$, 8월의 수심 50m는 3.5$^{\circ}C$ 정도 낮았고, 특히 홍도 외해는 5$^{\circ}C$나 낮았다. 그러므로 평년 보다 2.5~4.5$^{\circ}C$ 낮은 1981년 하계 황해 저층냉수의 이상저수온 현상은 전년 동계의 강한 북서 계절풍과 이상저기온에 기인된 표층해수의 냉각효과때문임이 밝혀졌다.

• Journal of Astronomy and Space Sciences
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• 제33권4호
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• pp.305-311
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• 2016

The spatial size and variation of Arctic sea ice play an important role in Earth's climate system. These are affected by conditions in the polar atmosphere and Arctic sea temperatures. The Arctic sea ice concentration is calculated from brightness temperature data derived from the Defense Meteorological Satellite program (DMSP) F13 Special Sensor Microwave/Imagers (SSMI) and the DMSP F17 Special Sensor Microwave Imager/Sounder (SSMIS) sensors. Many previous studies point to significant reductions in sea ice and their causes. We investigated the variability of Arctic sea ice using the daily sea ice concentration data from passive microwave observations to identify the sea ice melting regions near the Arctic polar ice cap. We discovered the abnormal melting of the Arctic sea ice near the North Pole during the summer and the winter. This phenomenon is hard to explain only surface air temperature or solar heating as suggested by recent studies. We propose a hypothesis explaining this phenomenon. The heat from the deep sea in Arctic Ocean ridges and/or the hydrothermal vents might be contributing to the melting of Arctic sea ice. This hypothesis could be verified by the observation of warm water column structure below the melting or thinning arctic sea ice through the project such as Coriolis dataset for reanalysis (CORA).

• Corrosion Science and Technology
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• 제23권2호
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• pp.83-92
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• 2024

A hot-dip simulator was utilized to replicate abnormal coating buildup observed during line stops at galvanize lines, assessing the influence of processing conditions on buildup (up to 14 mm/side). Steel samples from 19 coils (comprising IF, BH, LCAK, HSLA, DP600-DP1180, Si: 0.006 - 0.8 wt%, P: 0.009 - 0.045 wt%) were examined to explore the phenomenon of heavy coating growth. It was discovered that heavy coating buildup (~3 mm/h) and rapid strip dissolution (~0.17 mm/h) in a GA or GI pot can manifest with specific combinations of steel chemistry and processing conditions. The results reveal the formation of a unique coating microstructure, characterized by a blend of bulky Zeta crystals and free Zn pockets/networks due to the "Sandlin" growth mechanism. Key variables contributing to abnormal coating growth include steel Si content, anneal temperature, dew point in heating and soaking furnaces, Zn pot temperature, Zn bath Al%, and cold-rolling reduction%. At ArcelorMittal Dofasco galvanize lines, an automatic online warning system for operators and special scheduling for incoming Si-bearing steels have been implemented, effectively preventing further heavy buildup occurrences.

• 대기
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• 제16권3호
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• pp.187-201
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• 2006

During summer (JJA) of 2004, a record-high temperature in Korea appeared at Miryang ($38.5^{\circ}C$ on July 30). Moreover, Miryang showed the most frequent occurrence (25 days in JJA) of the daily highest temperature among observational sites in Korea. Based on meteorological analysis, it is found that this phenomenon is caused by neither the global warming effect nor the urban climate effect. It is caused by the mesoscale and synoptic and/or global scale atmospheric circulations, as evidenced by several factors described below. Firstly, the hottest areas have normally occurred not at a point but over an area, particularly along an axis connecting Sancheong and Daegu. But in 2004, this axis has moved southward and locates over Namhae-Miryang due to northerlies that were induced by the heating effect related to the low snow-cover on the Tibet Plateau. Secondly, although the maximum temperature was the highest among observational sites in Korea, the daily mean temperature and the number of nights with air temperature over $25^{\circ}C$ were not the highest at Miryang. Thirdly, the downdraft induced by the second circulation of typhoon and abnormal development of the North-Pacific High were found to have exerted an important role.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 춘계학술대회 논문집 전기설비전문위원
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• pp.131-133
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• 2008

This study presents on the analysis fire hazards of drum type electric washing machine. In order to analyze fire hazards fire experiment is conducted. The fire experiment is conducted to simulate under the normal condition and abnormal condition. The experiment under the abnormal condition is simulated in safety device failure, situation of accumulated dust and tracking phenomenon caused by humidity. The results show that fire hazard is high at the abnormal condition. In this paper, we suggest to use the safety device of low operating temperature in electric washing machine for reducing fire hazard.

• 전기학회논문지P
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• 제57권3호
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• pp.328-331
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• 2008

This study presents on the analysis fire hazards of drum type electric washing machine. In order to analyze fire hazards fire experiment is conducted. The fire experiment is conducted to simulate under the normal condition and abnormal condition. The experiment under the abnormal condition is simulated in safety device failure, situation of accumulated dust and tracking phenomenon caused by humidity. The results show that fire hazard is high at the abnormal condition. In this paper, we suggest to use the safety device of low operating temperature in electric washing machine for reducing fire hazard.

• 한국분말재료학회지
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• 제25권2호
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• pp.104-108
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• 2018

Grain-growth behavior in the $95Na_{1/2}Bi_{1/2}TiO_3-5BaTiO_3$ (mole fraction, NBT-5BT) system has been investigated with the addition of $Na_2CO_3$. When $Na_2CO_3$ is added to NBT-5BT, the growth rate is higher than desired and grains are already impinging each other during the initial stage of sintering. The grain size decreases as the sintering temperature increases. With the addition of $Na_2CO_3$, a liquid phase infiltrates the interfaces between grains during sintering. The interface structure can be changed to be more faceted and the interface migration rate can increase due to fast material transport through the liquid phase. As the sintering temperature increases, the impingement of abnormal grains increases because the number of abnormal grains increases. Therefore, the average grain size of abnormal grains can be decreased as the temperature increases. The phenomenon can provide evidence that grain coarsening in NBT-5BT with addition of $Na_2CO_3$ is governed by the growth of facet planes, which would occur via mixed control.

• 한국정밀공학회지
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• 제12권12호
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• pp.30-37
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• 1995

The mechanical seals, which are installed in rotating machines like pump and compressor, are gengrally used as sealing devices in the many fields of industries. The failure of mechanical seals such as leakage,fast and severe wear, excessive torque, and squeaking results in big problems. To monitor the failure of mechanical seals and to propose the proper monitoring techniques with artificial neural network, sliding wear experiments were conducted. Torque and temperature of the mechanical seals were measured during experiments. Optical microstructure was observed for the wear processing after every 10 minute sliding at rotation speed of 1750 rpm and scanning electron microscopy was also observed. During the experiment, the variation of torque and temperature that meant an abnormal phenomenon, was observed. That experimental data recorded were applied to the developed monitoring system with artificial neural network. This study concludes that torque and temperature of mechanical seals wil be used to identify and to monitor the condition of sliding motion of mechanical seals. An availability to monitor the mechanical seal failure with artificial neural network was confirmed.

• 통합자연과학논문집
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• 제17권2호
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• pp.33-41
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• 2024

Abnormal climate is a phenomenon in which meteorological factors such as temperature and precipitation are significantly higher or lower than normal, and is defined by the World Meteorological Organization as a 30-year period. However, over the past 30 years, abnormal climate phenomena have occurred more frequently around the world than in the past. In Korea, abnormal climate phenomena such as abnormally high temperatures on the Korean Peninsula, drought, heatwave and heavy rain in summer are occurring in March 2023. Among them, heatwaves are expected to increase in frequency compared to other abnormal climates. This suggests that heatwave should be recognised as a disaster rather than just another extreme weather event. According to several previous studies, greenhouse gases and meteorological factors are expected to affect heatwaves, so this paper uses logistic regression and discriminant analysis on meteorological element data and greenhouse gas data in Gwangju from 2008 to 2022. We analyzed the impact of heatwaves. As a result of the analysis, greenhouse gases were selected as effective variables for heatwaves compared to the past, and among them, chlorofluorocarbons were judged to have a stronger effect on heatwaves than other greenhouse gases. Since greenhouse gases have a significant impact on heatwaves, in order to overcome heatwaves and abnormal climates, greenhouse gases must be minimized to overcome heatwaves and abnormal climates.