• 식물병연구
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• 제25권2호
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• pp.71-78
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• 2019

2018년 전남 고흥군에서 발생한 유자나무의 집단 고사가 발생했다. 이에 대한 원인 조사를 위해 고흥군 풍양면에 있는 18개 유자 과수원을 무작위로 선정하여 조사를 수행한 결과 과수원별 고사증상을 보인 나무의 비율은 평균 43.6%(7.5%~100% 피해율), 증상을 보인 나무 중 56.5%는 나무 전체가 완전 고사되는 피해를 입은 것으로 나타났다. 고사 증상을 보인 대부분의 유자나무에서는 동해의 전형적인 증상인 표피 안 형성층과 목부의 갈변, 잎눈과 꽃눈의 무 발아, 가지나 줄기에 쪼개짐 증상 등이 관찰되었다. 따라서 기상 조건과 유자나무의 고사 증상이 연관 되어있을 것이라는 가설을 바탕으로 고흥지역의 과거 기상 자료를 분석하였다. 2017년 1월과 2월 고흥지역의 일평균 기온은 $-10^{\circ}C$ 이상이었으나, 2018년의 동 기간에는 $-10^{\circ}C$ 아래로 떨어진 날이 7일이나 되었다. 특히 2018년에는 1월과 2월에 유자의 내한성을 훨씬 넘어선 극최저기온(각각 $-12.6^{\circ}C$와 $-11.5^{\circ}C$)이 관측되었다. 또한 그해 3월 중순과 4월 초에 일 최저기온이 $13^{\circ}C$로 상승한 이상고온 직후 급격히 기온이 $0^{\circ}C$로 떨어지는 현상이 발생하였다. 결론적으로, 2018년 겨울철에 기록적인 극최저기온과 이상고온에 이은 급격한 기온의 저하로 인한 동해가 고흥지역에 대발생한 고사증상의 주요 원인이 되었을 것으로 추정하였다.

• 대기
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• 제25권1호
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• pp.31-49
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• 2015

From the hourly data of 75 Korean weather stations over a 12-year period (2001~2012), this study has chosen three cases (January 12, 2006; January 11, 2008; and February 22, 2009) of multiple freezing rains and investigated the atmospheric circulations that seemed to cause the events. As a result, the receding high pressure type (2006), prevailing high pressure type (2008), and warm front type (2009) are confirmed as synoptic patterns. In all three cases, freezing rain was found in regions with a strong ascending current near the end point of a low-level jet that carried the warm humid air from low latitudes. The strong ascending current resulted from lower-level convergence and upper-level divergence. In 2006 and 2009, the melting process was confirmed. In 2008, the supercooled warm rain process (SWRP) was confirmed. In contrast to existing SWRP theory, it was found that the cool air produced at the middle atmosphere and near the earth's surface led to the formation of freezing rain. The sources of this cool air were supposed to be the evaporative latent heat and the cold advection coming from the northeast. On the other hand, a special case was detected, in which the freezing rain occurred when both the soil surface temperature and surface air temperature were above $0^{\circ}C$. The thickness distributions related to freezing rain in Korea were found to be similar to those in North America. A P-type nomogram was considered for freezing rain forecasting; however, it was not relevant enough to Korea, and few modifications were needed.

• 동의생리병리학회지
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• 제19권1호
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• pp.196-203
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• 2005

Gunggui-tang has been used for the therapy of blood disorders in Hangbang medicine for long time. Also, Glycyrrhiza uralensis has been used for deficientblood patterns with an irregular pulse or palpitations, coughing and wheezing, and heat or cold in the lungs. Melanogenesis is a physiological process resulting in the synthesis of melanin pigments. We investigated whether the water extract of Gunggui-tang plus G. uralensis inhibited melanogenesis in B16 melanoma cells. Because the molecular events connecting the regulation in tyrosinase activity remain to be elucidated, we also aimed to determine whether Gunggui-tang gamibang(GTG) affects tyrosinase at the gene activation level in the cells. First, we showed that GTG inhibited the tyrosinase promoter activity and further, down-regulated the tyrosinase protein activity in ${\alpha}-melanocyte-stimulating$ hormone $({\alpha}-MSH)-treated$ B16 melanoma cells. GTG also resulted in a decrease of melanin content in MSH-induced melanogenesis, indicating that GTG may be a useful drug in studying the regulation of melanogenesis. The pretreatment of GTG significantly prevented phosphotransferase activity of c-Jun N-terminal kinase (JNK1) and transcriptional activation of activating protein-1 (AP-1) in MSH-treated B16 melanoma cells. These findings indicate that GTG inhibits melanogenesis of B16 melanoma cells via suppression of phosphotransferase activity of JNK1 and transcriptional activation of AP-1.

• Nuclear Engineering and Technology
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• 제26권1호
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• pp.63-77
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• 1994

이 연구는 가압경수로의 원자로 다운커머내에서 과도냉각시 직접용기주입에 따른 유체혼합현상을 가압열충격의 견지에서 시험모델을 사용하여 조사한 것이다. 시험모델은 ABB-CE System80＋ 원자로 구조에 근거하여 설계되었다. 이 원자로에 대한 가능성 있는 가압열충격 사고로서 콜드레그 소형파단 냉각재 상실사고와 주중기관 판단 사고가 선정되었다. 시험은 두 부분으로 구성되는데 첫째 부분은 원자로 다운커머에서 직접용기 주입수와 기존냉각재간의 유체혼합을 가시화법에 의하여 시험한 것이고, 둘째 부분은 별도의 시험모델에서 직접용기주입에 따른 열적혼합을 시험한 것이다. 가시화 시험에서는 과도적 냉각기간중 직접용기 주입수와 1차 냉각재간의 물리적 상호작용이 밝혀졌다. 열적혼합시험에서는 소형파단 냉각재 상실사고시 직접용기주입에 의한 심한 냉각현상이 다운커머내서 관찰되었다. 측정된 온도곡선은 소형파단 냉각재 상실사고에 대하여 REMIX 로드, 증기관 파단사고에 대하여는 COM-MIX-1B 코드에 의한 계산과 비교되었다.

• 대기
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• 제29권4호
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• pp.343-353
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• 2019

The seasonal climatology of atmospheric rivers (ARs) and their effects on the seasonal precipitation and temperature in Korea are examined using the AR chronology obtained by a methodology based on the vertically integrated water vapor transport (IVT) in conjunction with a fine-scale gridded analysis of station precipitation and temperature. ARs are found to affect Korea most heavily in the warm season with minimal impacts in winter. This contrasts the AR effects in the western North America and the Western Europe that are affected most in winters. Significant portions of precipitation in Korea are associated with AR landfalls for all seasons; over 35% (25%) of the summer (winter) rainfall in the southern part of the Korean peninsula. The percentage of AR precipitation over Korea decreases rapidly towards the north. AR landfalls are also associated with heavier-than-normal precipitation events for all seasons. AR landfalls are associated with above-normal temperatures in Korea; the warm anomalies increase towards the north. The warm anomalies during AR landfalls are primarily related to the reduction in cold episodes as the AR landfalls in Korea are accompanied by anomalous southerlies/southwesterlies.

• 대기
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• 제22권2호
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• pp.209-219
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• 2012

Extreme heavy snowfall episodes have been investigated in case of accumulated snowfall amount larger than 50 cm during the past ten years, in order to understand the association of low-level stability with heavy snowfall in the Yeongdong region. In general, the selected 4 events have similar synoptic setting such as the Siberian High extended to East Sea along with the Low passing by the southern Korean Peninsula, eventually inducing easterly in the Yeongdong region. Specifically moist-adiabatically neutral layer has been observed during the heavy snowfall period, which was easily identified using vertical profiles of equivalent potential temperature observed at Sokcho, whereas convective unstable layer has been formed over the East sea due to relatively warm sea surface temperature (SST) about $8{\sim}10^{\circ}C$ and lower temperature around 1~2 km above the surface, obtained from RDAPS. Difference of equivalent potential temperature between 850 hPa and surface as well as difference between air and sea temperatures altogether gradually increased before the snowfall period. Instability-induced moisture supply to the atmosphere from the East sea, being cooled and saturated by the upper cold surge, would make low-level ice cloud, and eventually move inland by the easterly flow. Heavy snowfall will be enhanced in association with low-level convergence by surface friction and upslope wind against Taebaek mountains. This study emphasizes the importance of low level stability in the Yeongdong region using the radiosonde sounding and RDAPS data, which should quantitatively be examined through numerical model as well as heat and moisture supply from the ocean.

• 대기
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• 제21권3호
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• pp.257-271
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• 2011

The aim of this study is to examine weather modification by urbanization and human activities. The characteristics of the urban heat island (UHI) and precipitation in Seoul metropolitan area of Korea are investigated to demonstrate that cities can change or modify local and nearby weather and climate, and to confirm that cities can initiate convection, change the behavior of convective precipitation, and enhance downstream precipitation. The data used in this study are surface meteorological station data observed in Seoul and its nearby 5 cities for the period of 1960 to 2009, and 162 Automatic Weather System stations data observed in the Seoul metropolitan area from 1998 to 2009. Air temperature and precipitation amount tend to increase with time, and relative humidity decreases because of urbanization. Similar to previous studies for other cities, the average maximum UHI is weakest in summer and is strong in autumn and winter, and the maximum UHI intensity is more frequently observed in the nighttime than in the daytime, decreases with increasing wind speed, and is enhanced for clear skies. Relatively warm regions extend in the east-west direction and relatively cold regions are located near the northern and southern mountains inside Seoul. The satellite cities in the outskirts of Seoul have been rapidly built up in recent years, thus exhibiting increases in near-surface air temperature. The yearly precipitation amount during the last 50 years is increased with time but rainy days are decreased. The heavy rainfall events of more than $20mm\;hr^{-1}$ increases with time. The substantial changes observed in precipitation in Seoul seem to be linked with the accelerated increase in the urban sprawl in recent decades which in turn has induced an intensification of the UHI effect and enhanced downstream precipitation. We also found that the frequency of intense rain showers has increased in Seoul metropolitan area.

• 한국환경과학회지
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• 제19권10호
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• pp.1187-1201
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• 2010

The formation and development conditions of the cloud streets over the yellow sea by the Cold Surge of Siberian Anticyclone Expansion which produce the heavy snowfall events over the southwestern coast, Honam District of the Korean peninsula, has been investigated through analyses of the three dimensional snow cloud structures by using the CAPPI, RHI, VAD and VVP data of X-band Radar at Muan Weather Observatory and S-band Radar at Jindo Weather Station. The data to be used are obtained from January 04, 2003, when heavy snow storm hits on Gwangju and Honam District. The PPI Radar images show that the cloud bands distribute in perpendicular to the expansion direction of the high pressure and that the radius of cloud cells is about 5~8 km with 20~30 dBz and distance between each cell is about 10 km. And but the vertical Radar images show that the cloud street is a small scale convective type cloud within height of about 3 km where a stable layer exists. From the VVP images, the time period of the high pressure expansion, the moving direction and development stages of the system are delineated. Finally, the vertical distribution of wind direction is fairly constants, while the wind speed sheer increases with altitude to 3 km.

• 한국작물학회지
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• 제49권2호
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• pp.148-153
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• 2004

The Hessian fly, Mayetiola destructor (Say), is known to be one of the major insect herbivores of wheat worldwide. In order to provide molecular events on interactions of the NIL with H21 and larvae of Hessian fly biotype L, the TaCR1 gene, Triticum aestivum cytokinin repressed 1, was isolated through the suppression subtractive hybridization, which was constructed using stems of the NIL with H21 at 6 days after infestation as tester and stems of the recurrent parent Coker797 without H21 at 6 days after infestation as driver. Transcript levels of TaCR1 mRNA in the NIL with H21 were highest at 6 days after infestation but in the Coker797 without H21 until 8 days were similar with those of non-infested plants. Expression of the TaCR1 gene was decreased at early time and then recovered after wounding or $H_2O$$_2$ treatment as well as 6-BAP treatment. Transcripts levels of the TaCR1 gene was changed after MeJA, SA, ethephone, or ABA treatment. In drought treatment, the TaCRl gene were increased at early stage of stress and then decreased at late stage. Expression of the TaCRl gene was continued to decrease through 24 h in the cold treatment. Although the TaCRl gene is increased through infestation in NIL with H21, further study was required to elucidate a role on resistance against larvae of Hessian fly. However, the TaCR1 gene could be used as marker gene on response of plants against abiotic stresses as well as application of plants with several hormones.

• 대기
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• 제29권2호
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• pp.183-196
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• 2019

High-quality and high-resolution meteorological information is essential to reduce damages due to disastrous weather phenomena such as flash flood, strong wind, and heat/cold waves. There are many meteorological observation stations operated by Korea Meteorological Administration (KMA) in Seoul Metropolitan Area (SMA). Nonetheless, they are still not enough to represent small-scale weather phenomena like convective storm cells due to its poor resolution, especially over urban areas with high-rise buildings and complex land use. In this study, feasibilities to use additional pre-existing networks (e.g., operated by local government and private company) are tested by investigating the effects of network density on the gridded horizontal distribution of two meteorological variables (temperature and precipitation). Two heat wave event days and two precipitation events are chosen, respectively. And the automatic weather station (AWS) networks operated by KMA, local-government, and SKTechX in Incheon area are used. It is found that as network density increases, correlation coefficients between the interpolated values with a horizontal resolution of 350 m and observed data also become large. The range of correlation coefficients with respect to the network density shows large in nighttime rather than in daytime for temperature. While, the range does not depend on the time of day, but on the precipitation type and horizontal distribution of convection cells. This study suggests that temperature and precipitation sensors should be added at points with large horizontal inhomogeneity of land use or topography to represent the horizontal features with a resolution higher than 350 m.