복합지형상에서 비정상 박리흐름에 의한 확산

류찬수,Ryu, Chan-Su 한국지구과학회 2001 한국지구과학회지 Vol.22 No.6

복합지형을 지나는 박리흐름(separated flows)들이 와도 이론에 의해 모델링 되었다. 흐름은 비회전성 및 비점성으로 가정하였으며, 선형 시어흐름에 대한 유선함수를 결정하기 위해 새로운 기법이 기술되었다. 지형지물의 형태로는 snow cornice과 backward-facing step을 정의하였으며, 이러한 지형지물의 후미에는 유체의 박리현상과 역류현상(reattachment)이 생긴다. 유체의 박리현상이 지형지물의 가장자리에 발생되게 하기 위해 점 와도를 흐름에 발생시켰고, 지형지물의 가장자리에 있는 뾰족한 부분을 완화하고 최대곡률 부근에서의 섭동운동에 중요한 박리흐름 발생지점의 구속조건을 없애기 위해 conformal mapping을 수정하였다. 와도 발생지점에서 와도를 평형으로부터 이동시키거나, 또는 임의의 섭동을 초기흐름에 가하는 방식으로 섭동을 가하여 비정상흐름을 발생시켰다. 박리지점의 풍상측에서 연속적으로 방출되고, 또한 bubble의 이차순환에 의해 변형된 물질의 궤적들이 수치적으로 적분되었으며, 시간에 대한 농도누적이 역류지점의 풍하측 고정된 지점에서 계산되었다. 본 연구에 사용된 모델은 방출물질의 확산형태와 간헐성을 제대로 다룰 수 있음을 알 수 있으며, 이산적인 방법에 의한 다중-와도모델 및 수치모델의 결과들과도 일치한다. 본 연구에 의하면, 박리 및 역류현상이 있는 유체의 흐름 속에 순환하는 bubble들의 비정상상태(unsteadiness)는 풍하측에서 대규모의 고농도 누적을 일으키는 주요 원인이다. Separated flows passed complex geometries are modeled by discrete vortex techniques. The flows are assumed to be rotational and inviscid, and a new techlnique is described to determine the stream functions for linear shear profiles. The geometries considered are the snow cornice and the backward-facing step, whose edges allow for the separation of the flow and reattachment downstream of the recirculation regions. A point vortex has been added to the flows in order to constrain the separation points to be located at the edges, while the conformal mappings have been modified in order to smooth the sharp edges and to let the separation points free to oscillate around the points of maximum curvature. Unsteadiness is imposed to the flow by perturbing the vortex location, either by displacing the vortex from the equilibrium, or by imposing a random perturbation with zero mean to the vortex in equilibrium. The trajectories of passive scalars continuously released upwind of the separation point and trapped by the recirculating bubble are numerically integrated, and concentration time series are calculated at fixed locations downwind of the reattachment points. This model proves to be capable of reproducing the trapping and intermittent release of scalars, in agreement with the simulation of the flow passed a snow cornice performed by a discrete multi-vortex model, as well as with direct numerical simulations of the flow passed a backward-facing step. The results of simulation indicate that for flows undergoing separation and reattachment the unsteadiness of the recirculating bubble is the main mechanism responsible for the intense large-scale concentration fluctuations downstream.

고층관측자료에 나타난 서해중부해상에서 바람의 연직구조 변화

류찬수(Chan-Su Ryu),안명환(Myung-Hwan Ahn) 한국자료분석학회 2003 Journal of the Korean Data Analysis Society Vol.5 No.2

The wind data obtained form intensive upper-air observation at Oeyond, which is located in middle part of Yellow Sea, from 10 to 14 April, 1999 are used in this study in order to examine the variation of vertical wind structure over the Yellow Sea. At 15 LST 12 April when minimum surface pressure was recorded at Oeyondo, there appeared the abrupt change of wind direction. The change of wind orthogonality become larger under the influence of immigrating high pressure system than under the influence of low pressure system. Larger value of wind shear at 200-300m height than other height is closely linked with the appearing height of low-level strong wind induced from the combined effects of the presence of surface and low-level inversion layers and the topographical location of observation site. Maximum value of vorticity computed by the line integral method is present at 15 LST 12 April. Also vorticity shows negative vorticity in the first half of intensive observation period and positive one in the second half, which means the well reflection of the synoptic weather condition. Maximum value of divergence reveals at 21 LST 12 April lagged by six hours compared to the appearing time of maximum value of vorticity. This result provides useful experimental evidence in evaluation of impact of additional upper-air observation at middle part of Yellow Sea on improved diagnostic skill of synoptic weather system approaching to the Korean peninsula. 1999년 4월 10일부터 4월 14일까지 서해중부해상에 위치한 외연도에서 실시된 고층기상관측으로 얻은 바람 자료를 이용하여 해상에서 바람의 연직구조 변화를 조사하였다. 외연도에 최저기압이 관측된 4월 12일 15LST경을 기준으로 풍향의 갑작스런 변화가 있었다. 바람의 직교성은 관측기간중 이동성 고기압의 영향하에서 크게 나타났다. 바람의 연직시어는 역전층 존재 고도 등 대기 열역학적 연직구조 특성과 관측지점의 지형효과로 인하여 나타나는 하층 강풍으로 인하여 고도 200-300m에서 큰 값을 보였다. 또한 혼합층 고도의 상한은 주로 풍향의 변화가 심하고 연직시어가 큰 고도에 위치하였다. 선적분법에 의해 계산된 와도의 최대값은 외연도에서 최저기압이 기록된 시각에 나타났고, 발산은 대체로 저기압의 영향을 받는 관측기간의 전반부에서 음의 발산값(수렴)을 보이다가 와도의 최대값이 나타난 시각인 12일 15LST보다 6시간이 지연된 21LST부터 양의 발산값(발산)으로 전환하였다. 이는 저기압 통과후 이동성 고기압의 영향 때문으로 해석된다. 이러한 연구결과는 서해상에서 악기상 발생 및 발달시, 해상의 특별고층관측자료와 육지 고층관측자료를 이용하여 악기상 관련 종관 기압계의 이동 및 발달을 조기에 진단할 수 있음을 보여주는 실험적 자료로 활용될 수 있다.

폭설에 대한 예측가능성 연구 -2008년 3월 4일 서울지역 폭설사례를 중심으로

류찬수 ( Chan Su Ryu ),서애숙 ( Ae Sook Suh ),박종서 ( Jong Seo Park ),정효상 ( Hyo Sang Chung ) 한국환경과학회 2009 한국환경과학회지 Vol.18 No.11

광주 지방의 강수량 변화와 Anomalies

류찬수(Ryu Chan Su) 조선대학교 교과교육연구소 1999 교과교육연구 Vol.20 No.1

In this paper it is discussed about interannual variation characteristics of precipitation amount of Kwangju and relationship with the SST anomaly. The daily data from 1940 to 1997 were used for precipitation amount and 2.5×2.5˚ grid of NOAA is also used for SST. The annual mean precipitation amount of Kwangju was 1287.5㎜, standard deviation was 306㎜, and variability was 23.77%, and then absolute variable value was 349㎜. The precioitation amount had a tendency to increase at 2.1㎜/year and the amplitude increased at ±3.77㎜/year. The positive anomaly of the precioitation amount presented seven times and the negative anomaly did eleven times. The annual mean precioitation days were 126.2 and standard deviation was 12.77, variability was 10.1% and then the absolute variable value was 9.77.We can conclude that the SST distribution of the North Pacific is the one factor of precioitation amount change of Kwangju.

일기 엔트로피 및 정보비를 이용한 예보구역의 설정(Ⅰ) : 일기 엔트로피의 분포 특성을 중심으로

류찬수(Chan-Su Ryu),박현욱(Hyun-Wook Park) 한국자료분석학회 2000 Journal of the Korean Data Analysis Society Vol.2 No.4

The seasonal variation of Korea peninsula shows strong local weather phenomenon because of its geographical factors in Northeast side of the Asia. The representativeness of weather and yearly changes applicate this strong local weather phenomenon. In this study, weather entropy is evaluated statistically trough application of information theory on strong typical weather and yearly change types at 69 sites in South Korea. Through that way, the characteristics of the region is studied by analysis of the time change of the space scale the characteristics of the region and is compared to real climate characteristics. 한반도는 아시아 대륙의 북동쪽에 위치하며 지형이 복잡하여 특정 일기의 종류, 빈도와 계절적 변화의 국지성이 강하다. 이러한 특정 일기의 특징은 일기 출현율과 연변화 상에 잘 반영되고 있다. 본 논문에서는 남한의 69개 관측지점의 특정 일기(운량 및 강수현상)의 빈도와 그 연변화형에 대해 정보이론을 이용하여 일기 엔트로피 연 변화를 통계적으로 분석하고, 그 공간스케일의 시간적 변동을 규명해 그 지역적 분포 특성을 살피고, 실제 일기의 특성과 비교하였다.

2005년 12월에 발생한 호남대설의 발달 환경에 관한 연구

류찬수 ( Chan Su Ryu ),이순환 ( Soon Hwan Lee ),박철홍 ( Cheol Hong Park ) 한국환경과학회 2007 한국환경과학회지 Vol.16 No.12

해안지형 복잡성이 중규모순환장에 미치는 영향에 관한 수치실험

류찬수(Chan-Su Ryu),신유미(Yoo-Mi Shin),이순환(Soon-Hwan Lee) 한국기상학회 2004 Asia-Pacific Journal of Atmospheric Sciences Vol.40 No.1

우리나라 南西海岸의 海陸風 探究

Seung Hee Lee(李承姬),Chan Su Ryu(柳贊洙) 조선대학교 교과교육연구소 2000 교과교육연구 Vol.21 No.1

Geographically, Three sides of Korea are surrounded by the sea(that is, the Korean Peninsular). Accordingly, the environment of our country has been greatly affected by the sea. For this study and taking an observation with AWS. I’ve selected the Mokpo city to which Taebul industrial complex is adjacent and Seochon, the central part of the western coast to which Asan industrial complex is adjacent. I’ve utilized the data on the Mokpo city which were supplied by the Mokpo observatory. I’ve confirmed the change of the direction and the speed of the breeze of two areas(Mokpo and Seochon) through classifying all the data of the annual breeze into a daily unit, a monthly unit and a seasonal unit. As a result, there was a more vivid sea and land breeze character in Seochon area than in Mokpo area. And an average speed of breeze of Mokpo was greater than that of Seochon area. It can be inferred that the more speedy breeze in Mokpo area is due to the Mokpo’s geographical location. In the frequency of breeze direction, NNW direction which occupied 27% of the whole was prevailing and in the frequency of breeze speed, the range of 0.3~3.3㎧ appeared frequently, and it showed 48.9%. According to rarity analysis on the relations between breeze direction and breeze speed, a correlation coefficient was 0.56~0.91 and through it. I could figure out correlation of breeze direction and breeze speed. But it is matter of regret that this study has a statistical analytic basis mainly, so, from now on, I intend to do profound research on factors which cause the change of sea and land breeze and I’d like to develop them to be processed as environmental factors.

여수지역의 기후특성에 따른 산업화 개발 응용

김재호(Kim Jae-Ho),류찬수(Ryu Chan-Su) 조선대학교 지식경영연구원 2004 지역개발연구 Vol.9 No.1

The Yeosu peninsular has the best agreeable climate for human living in Korea, which has the good climate conditions with tourism attractions and a nation recreation center. The annual mean air temperature is 14.1℃ in the Yeosu peninsula. It's monthly mean air temperature on August which records the highest air temperature is 25.7℃ and it's the lowest air temperature is 2.2℃ which records on January, the monthly mean air temperature for all months stays above 0℃. We can notice that the tendency of air temperature has became higher for last 5 years at the Yeosu peninsula. The highest extreme value air temperature records 37.1℃ on July 20, 1994. and the lowest extreme value were -12.6℃ on February 16, 1977. The annual rainfall amount is 1407.5㎜ and 80.9% of rainfall is concentrated in 6 months from April to September. It is region that the Yeosu peninsular have much rainfall, but the disaster from heavy rain is few. The annual mean wind velocity is 3.9㎧. It has significant wind direction that shows NE for spring and fall. SW and SE for summer and NW for winter. We can apply the various climate classification methods for the Yeosu peninsular. There are many instances that Koppen's method classified it is "Cf", Strahler is "Cfa". Trewartha is "Do". By the other way, on the classification that adopts the small climate division method of Korea: the S. McCune's method is "middle southern coast climate", S. O. Kang is "Dadohae climate", K. S. Kim is "Namhaean-type climate". Specially, the climate classification into which, J. B. Lee apply cumulative stress is classified into "very comfortable climate". The following shows climate environment application and the tendency of special development of community for the Yeosu peninsula.. 1) Public relations of the optimum climate environment and development of oceanic tripㆍleisure 2) Building of a nation recreation center 3) Specialization development of leisure sport and athletics ground 4) Furtherance of theme park Meteorological and Earth-science experience 5) Necessity of establishment meteorological company in Yeosu region 6) Use for source of nature energy(proper wind velocity, abundant sunshines with fine days)

논문 : 지구환경과 교육 ; 하층제트와 지리산집중호우의 상호 관련성에 관한 수치연구

이순환 ( Soon Hwan Lee ),류찬수 ( Chan Su Ryu ) 한국지구과학회 2004 지구과학 교육심포지엄 및 춘계학술발표회 Vol.2004 No.-