북서태평양에서 발생한 태풍에 대해 발생 후 5일 동안 12시간 간격으로 태풍의 강도 및 진로를 예측할 수 있는 인공신경망 모델을 개발하였다. 사용되어진 예측인지는 CLIPER(발생 위치 강도 일자), 운동학적 파라미터(연직바람시어, 상층발산, 하층상대와도), 열적 파라미터(상층 상당온위, ENSO, 상층온도, 중층 상대습도)로 구성되어졌다. 예측인자의 특성에 따라 일곱개의 인공신경망 모델들이 개발되었으며, CLIPER와 열적 파라미터가 조합된(CLIPER-THERM) 모델이 가장 좋은 예측성능을 보였다. 이 CLIPER-THERM 모델은 강도 및 진로 모두에서 동절기보다 하절기에 더 나은 예측성능을 나타내었다. 또한 태풍의 발생이 아열대 서태평양의 남동쪽에 위치할수록 강도예측에서는 큰 오차를 보였고, 진로예측에서는 아열대 서태평양의 북서쪽에서 발생할수록 큰 오차를 보였다. 이후 인공신경망 모델의 예측성능을 검증하기 위해 같은 예측인자들을 이용하여 다중선형회귀모델을 개발하였으며, 결과로서 비선형 통계기법인 인공신경망 모델이 다중선형회귀모형보다는 더 나은 예측성능을 보였다.

이 연구는 태풍의 온대성 저기압화에 대해 간단히 소개하고 Evans and Hart(2003)와 Hart(2003의 객관적 온대성 저기압화 판별식을 이용하여 최근 온대성 저기압화를 거친 세 태풍(Shanshan, Yaki, Soulik)에 대한 사례분석이 이루어졌다. 500-hPa 고도장분석에서 온대성 저기압화 시작시 세 태풍 모두 중위도 경압지역으로 북상하는 공통된 특성을 보였다. 그러나 연직단면 분석에서는 온대성 저기압화의 시작전 시 태풍 중심부근의 모든 층에서 온난 다습한 특성을 보였다. 온대성 저기압화 이후에는 이 개념모델의 전형적 특성인 태풍의 서쪽영역에 한랭 건조한 특성을 나타내었다. 따라서 Evans and Hart(2003)와 Hart(2003)의 객관적 온대성저기압화의 판별식은 태풍의 온대성저기압화 시작 및 구조변화를 잘 반영하므로 기상청 예보현업에서도 유용하게 사용될 수 있을 것으로 판단된다.

원자력연구소 핫셀의 구조와 오염특성이 조사되었다. SEM 측정결과 핫셀 내부에 부착된 고방사능 분진의 크기는 이었다. 사이클론의 최적 Vortex finder의 길이는 49 mm이고, 모의입자 유입속도는 15m/sec가 적합했다. 이때 의 포집효율은 약 85%였다. 모의 입자 유입속도가 15m/sec보다 빠를 때, 포집효율의 증가율은 크지 않았다. 유입가스의 온도가 증가할 때, 포집효율은 약간 감소했다. Vortex finder의 길이가 증가할수록 사이클론내의 압력강하는 커졌다. Cut size diameter는 Reynolds number의 증가와 함께 감소했다. 측정된 Reynolds number에 근거하면, 사이클론 내부는 난류이고 이 난류는 사이클론 내의 압력강하에 원인이 된다고 사료된다. 는 Re 값의 증가와 함께 감소하고, Re의 값이 커질 때에서 일정한 값에 수렴했다. 즉, 6000-8000의 Re에서 는 약 0.045를 나타냈다.

원자력시설 핫셀 (Hot Cell)내에서 핵종실험 시 발생하는 고방사능 분진(Hot Particulate)의 크기는 0.5300 이고 주 핵종은 UO였다. 핫셀 내의 고방사능 분진을 제거하기 위해 사이클론과 Bag/HEPA필터로 구성된 장치를 고안하였고, 이 장치의 사이클론에 의해 고방사능 분진을 최대로 포집할 수 있는 실험조건을 제시했다. 모의입자의 크기가 클수록 입자의 포집효율은 높았다. 모의 입자의 크기가 5 이상일 때, 입자의 포집효율은 보다 높았다. 모의 입자의 크기가 1.0 보다 작을 때, 포집효율은 보다 작았다. 모의 입자의 유입속도가 12 m/sec보다 클 때, 포집효율은 보다 높았다. 그러나 유입속도가 17 m/sec 보다 클 때 포집효율의 증가율은 크지 않았다. 모의입자의 포집효율은 Vortex Finder의 길이가 7.2 cm이하일 때, 길이의 증가와 함께 높아졌지만 7.2 cm 이상일 때는 낮아지기 시작했다. 그러므로 Vortex Finder의 길이가 7.2 cm 일 때, 최대포집효율을 나타냈다. 사이클론 밑에 보조콘 부착 시 모든 속도 범위에서 약 평균 정도 포집효율이 증가하므로 보조콘 부착효과가 크지 않았다.

This study evaluated the performance of GFDL HiRAM, a fine resolution AGCM, in the simulation of GPI (Genesis Potential Index) of tropical cyclone and its temporal variation over the Western North Pacific (WNP). We analyzed the AMIP simulation by the AGCM for the 30-year (1979-2008) forced by observed sea surface temperatures as the lower boundary condition. Since GPI depends on the five large-scale environmental factors(850 hPa absolute vorticity, 700 hPa relative humidity, vertical wind shear, maximum potential intensity, and 500 hPa vertical velocity), the biases of the simulation are examined for these factors as well as GPI itself. The results are compared with the ECMWF Interim reanalysis (ERA-I), and the analyses show that both the mean spatial pattern and the seasonal cycle of GPI over the WNP are reasonably simulated by HiRAM. But the magnitude of GPI is significantly underestimated due to the combined contribution of negative biases in four factors excluding the low-level vorticity. It is demonstrated that the three leading modes of spatio-temporal variability of GPI in EOF analysis for ERA-I are associated with ENSO, climate change with long-term trends, and SST anomalies over the WNP. The response of GPI to ENSO is more or less captured by HiRAM, including the east-west shift of Typhoon genesis location. However, it is supposed that unrealistic response of GPI and its factors to La-Nina or eastern Pacific El-Nino is an important shortcoming of HiRAM. In addition, HiRAM fails to reproduce the characteristic spatiotemporal variation associated with the climate change mode of GPI. The key findings from this study provide helpful guidance for improvement of HiRAM.

Solar activity is known to be linked to changes in the Earth’s weather and climate. Nonetheless, for other types of extreme weather, such as tropical cyclones (TCs), the available evidence is less conclusive. In this study the modulation of TC genesis over the western North Pacific by the solar activity is investigated, in comparison with a large-scale environmental parameter, i.e., El-Niño-Southern Oscillation (ENSO). For this purpose, we have obtained the best track data for TCs in the western North Pacific from 1977 to 2016, spanning from the solar cycle 21 to the solar cycle 24. We have confirmed that in the El-Niño periods TCs tend to form in the southeast, reach its maximum strength in the southeast, and end its life as TSs in the northeast, compared with the La-Niña periods. TCs occurring in the El-Niño periods are found to last longer compared with the La-Niña periods. Furthermore, TCs occurring in the El-Niño periods have a lower central pressure at their maximum strength than those occurring in the La-Niña periods. We have found that TCs occurring in the solar maximum periods resemble those in the El-Niño periods in their properties. We have also found that TCs occurring in the solar descending periods somehow resemble those in the El-Niño periods in their properties. To make sure that it is not due to the ENSO effect, we have excluded TCs both in the El-Niño periods and in the La-Niña periods from the data set and repeated the analysis. In addition to this test, we have also reiterated our analysis twice with TCs whose maximum sustained winds speed exceeds 17 m/s, instead of 33 m/s, as well as TCs designated as a typhoon, which ends up with the same conclusions.

This study analyzes the characteristics of Western North Pacific (WNP) tropical cyclone (TC) activity and large-scale environments according to the Western Pacific (WP) teleconnection pattern in summer. In the positive WP phase, an anomalous cyclone and an anomalous anticyclone develop in the low and middle latitudes of the East Asia, respectively. As a result, southeasterlies are reinforced in the northeast area of the East Asia including Korea and Japan which facilitates the movement of TC to this area, whereas northwesterlies are reinforced in the southwest area of the East Asia including South China and Indochina Peninsula which blocks the movement of TC to this area. Due to the spatial distribution of this reinforced pressure system, TCs develop, move, and turn more to the northeast of WNP than those in the negative WP phase. Consequently, the characteristics of this TC activity in the positive WP phase are associated with the location of upper tropospheric jet further to the northeast. Meanwhile, TCs in the negative WP phase mainly move to the west from Philippines toward south China and Indochina Peninsula. Furthermore, due to the terrain effect caused by the high passage frequency of TCs in the mainland China, the intensity of TCs are weaker than those in the positive WP phase.

This study analyzed the change in tropical cyclone (TC) activity according to the fluctuation in July-to-September average North Pacific Oscillation index (NPOI) and its underlying large-scale environment during the last 37 years from 1977 to 2013. For this purpose, seven years with highest index NPOI value (positive NPOI phase) and another seven years with lowest NPOI index value (negative NPOI phase) among the 37 years were selected as sample after excluding the ENSO years. During the positive NPOI phase, TCs were created in the east of tropical and subtropical western North Pacific and moved to the west from the Philippines toward the southern region in China or toward far eastern sea of Japan. Meanwhile, during the negative NPOI phase, TCs tended to proceed to the north toward Korea or Japan passing East China Sea from the eastern sea of the Philippines. As a result, also in the TC recurvature, TCs in positive NPOI phase showed a tendency of recurving toward more eastern direction compared to TCs in negative NPOI phase. Hence, TC intensity was stronger in negative NPOI phase which allowed more time for obtaining energy from the ocean.

In order to obtain the optimal design of a char removal cyclone, the effect of the vortex finder height and inlet shapeon its performance are numerically carried out. The pressure drop and collection efficiency are calculated for four differentcyclones with different vortex finder heights and inlet shapes. To validate the present numerical process, the calculatedpressure drops for two types of cyclones are compared with experimental results and the results show a good agreementbetween experimental and numerical results. From the results, increasing the height of the vortex finder, the collectionefficiency is increased. As for cyclone inlet shapes, the tangential one is characterized by lower efficiency compared withthe volute counterpart. The current result can be used for the design of cyclones with high collection efficiency, especiallyfor removing tiny char which is generated during fast pyrolysis process of waste biomass.

This study recognized five annual cycle modes of the tropical cyclone (TC) activity in the western North Pacific using the CMA-STI data by an objective-oriented K-means cluster analysis approach. The five annual cycle modes include one normal mode and four abnormal modes: a weakened mode, two enhanced modes, and an anti-seasonal mode which suggests TC activities are enhanced in early season but suppressed in peak season. The yearly storm number and storm lifespan of both the weakened mode and the anti-seasonal mode are different from those of the two enhanced modes. The annual amplitudes of TC activity seem to be closely associated with the area of TC genesis. The discrepancies are obvious in frequencies of the five modes. However, comparison with both JMA and JTWC data suggests that the seasonality of TC activity has large bias.

In this paper, changes in the intensity (e.g., central pressure and maximum sustained wind speed) of Tropical Cyclone (TC) in summer in the regions located at 30 oN in East Asia from 1988 to 1991 were found. The intensity of TC from 1991 to 2007 was much higher than that of TC from 1965 to 1988. The reason for this was that the frequency of TCs passing China from 1991 to 2007 was much lower than that of TCs from 1965-1988 because a northeasterly wind caused by high-pressure circulation in East Asia got severer along the East Asian coast. Instead, TCs moved from the eastern region of the Tropical West Pacific to Korea and Japan mainly after passing the East China Sea due to the low-pressure circulation strengthened in the subtropical waters of East Asia. In addition, low Vertical Wind Shear (VWS) was created along the mid-latitude regions of East Asia and the main path of TCs from 1991 to 2007. Most of the regions in the Northwestern Pacific showed higher Sea Surface Temperature (SST) from 1991 to 2007, and had a good environment where TCs were able to maintain a higher intensity on the mid-latitude. In particular, a low sensible heat flux occurred due to high snow depth in East Asia in the spring of 1991 to 2007. Accordingly, the lower layer of East Asia showed high-pressure circulation, and the sea surrounding East Asia showed low-pressure circulation. Thus, the typical west-high, east-low pattern of winter atmospheric pressure was shown. The possibility of snowfall in East Asia in spring to be used as a factor for predicting the summer intensity of TC in the mid-latitude regions of East Asia was insinuated. The characteristics of TC in a low-latitude region were the same in Korea. The latest intensity of TCs got higher, and the landing location of TCs gradually changed from the west coast to the south coast.

겨울철 한반도와 부근 해역은 대륙에서 발달하는 시베리아고기압과 해양에서 발달하는 알류샨저기압으로 형성되는 전형적인 서고동저형의 기압배치의 영향을 많이 받는다. 이 기압배치의 영향으로 우리나라와 주변 해역, 특히 서해에서는 강한 서풍 내지 북서풍의 계절풍과 강한 바람에 의한 높은 파랑, 폭설 등을 동반하는 악기상이 빈번히 발생한다. 이 연구에서는 겨울철에 서해에서 활동하는 국가어업지도선의 안전한 피항지를 선정하기 위하여 11년간 (1994-2004년)의 지상일기도를 분석하여 온대저기압의 주요 이동경로를 구분하였다. 그리고 온대저기압의 이동경로별로 섬들의 지형적 특성, 수심, 저질의 상대, 조류의 영향 및 어망의 분포 등을 조사하고, 그 결과를 이용하여 서해에서 활동하는 국가어업지도선의 안전한 피항지를 선정하였다.