• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2018년도 학술발표회
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• pp.499-499
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• 2018

Hydro-meteorological extremes are trivial in these days. Therefore, it is important to identify extreme hydrological events in advance to mitigate the damage due to the extreme events. In this context, exploring temporal distribution of sub-daily extreme rainfall at multiple rain gauges would informative to identify different states to describe severity of the disaster. This study proposehidden Markov chain model (HMM) based rainfall analysis tool to understand the temporal sub-daily rainfall patterns over South Korea. Hourly and daily rainfall data between 1961 and 2017 for 92 stations were used for the study. HMM was applied to daily rainfall series to identify an observed hidden state associated with rainfall frequency and intensity, and further utilized the estimated hidden states to derive a temporal distribution of daily extreme rainfall. Transition between states over time was clearly identified, because HMM obviously identifies the temporal dependence in the daily rainfall states. The proposed HMM was very useful tool to derive the temporal attributes of the daily rainfall in South Korea. Further, daily rainfall series were disaggregated into sub-daily rainfall sequences based on the temporal distribution of hourly rainfall data.

• Archives of Plastic Surgery
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• 제32권2호
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• pp.214-218
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• 2005

The anatomy and distribution of the superficial temporal vessels are known to follow regular patterns, with few exceptions in previous studies. But these previous studies of the anatomy and distribution of the superficial temporal vessels were based, only on the cadaver studies. Authors evaluated the anatomy of these vessels in the operative field of the living body from December 1997 to June 2001, The superficial temporal vessels were surgically exposed from the zygomatic arch extending to the superior temporal line through a preauricular incision in 18 patients(20 cases), who underwent reconstructive surgery using these vessels in the operative field. The authors measured and analyzed; the distribution, branching and diameters of the superficial temporal vessels. The results were obtained as follows; 1.In 19 cases, STV(superficial temporal vein) runs posterior to STA(superficial temporal artery) at the upper border of the zygomatic arch. 2. There was no frontal or parietal branches in 2 cases and vena comitante existed along with STA in one case. 3. The external diameter of STA and STV was measured at the lower border of the zygomatic arch. The external diameter of STA ranged from 1.5 mm to 3.0 mm(average 2.1 mm) and those of STV ranged from 1.3 mm to 3.5 mm (average 2.0 mm). This study can be helpful in the reconstructive surgery using the superficial temporal vessels, for the results of our study are based on the true anatomy of the living body.

• 한국통신학회논문지
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• 제21권6호
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• pp.1361-1369
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• 1996

Motion estimation is one of the key components for high quality video coding. In this paper, a new motion estimation scheme for MPEG-like video coder is suggested. The proposed temporally adaptive motion estimation scheme consists of five functional blocks: Temporal subband analysis (TSBA), extraction of temporal information, scene change detection (SCD), picture type replacement (PTR), and temporally adapted block matching algorithm (TABMA). Here all the functional components are based on the temporal subband analysis. In this papre, we applied the analysis part of subband decompostion to the temporal axis of moving picture sequence, newly defined the temporal activity distribution (TAD) and average TAD, and proposed the temporally adapted block matching algorithm, the scene change detection algorithm and picture type replacement algorithm which employed the results of the temporal subband analysis. A new block matching algorithm TABMA is capable of controlling the block matching area. According to the temporal activity distribution of objects, it allocates the search areas nonuniformly. The proposed SCD and PTR can prevent unavailable motion prediction for abrupt scene changes. Computer simulation results show that the proposed motion estimation scheme improve the quality of reconstructed sequence and reduces the number of block matching trials to 40% of the numbers of trials in conventional methods. The TSBA based scene change detection algorithm can detect the abruptly changed scenes in the intentionally combined sequence of this experiment without additional computations.

• 한국대기환경학회지
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• 제19권2호
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• pp.191-204
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• 2003

A one dimensional time dependent acid rain model considering size distribution of aerosols and hydrometeors is developed to predict observed chemical and physical properties of precipitation. Temporal variations of anions and cations observed are predicted fairly well with acid rain model simulations. It is found that aerosol depletion rates are highly dependent on aerosol sizes under the assumption of Marshall - Palmer raindrop size distribution. Also, the aerosol depletion during the initial rain event largely influences on ion concentrations in rainwaters.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2003년도 Proceedings of ACRS 2003 ISRS
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• pp.231-233
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• 2003

Agricultural land use generally shows specific temporal characteristics of NDVI obtained from satellite data. In terms of winter wheat, a higher value compared with other land use types in May and a considerably low value in June could be discriminative features of temporal change of NDVI. In this study, the author examined methods for estimating winter wheat sown area in sub-pixel level of coarse resolution satellite data using temporal characteristics of NDVI. Application of the methods to the major grain production area in China exhibited properly a spatial distribution pattern of winter wheat sown area.

• 한국수자원학회논문집
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• 제55권4호
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• pp.257-266
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• 2022

국지성 호우 및 설계빈도 이상 강우의 증가로 침수피해가 매년 증가하고 있으며 이에 따라 홍수 조절 및 방어를 위한 수공구조물의 중요성이 증가하고 있다. 수공구조물은 목적과 성능에 따른 설계가 이루어지고 있고 홍수량이 중요한 산정 요소이나 국내에서는 관측자료의 신뢰성 부족 및 데이터의 부족으로 인하여 수공구조물 설계를 위한 수문해석 입력자료로 사용되는 설계강우량은 정확한 확률강우량의 산정과 시간분포가 중요한 요소로 작용한다. 실무에서는 Huff의 4분위 방법의 누가우량백분율을 이용하여 설계강우량의 시간분포 회귀식을 산정하고 있으며 분위별 곡선에 대한 회귀식은 전반적으로 정확도가 높게 나타나는 6차 다항회귀식을 일률적으로 사용하고 있다. 본 연구에서는 실무에서 일반적으로 설계강우량의 시간분포를 위해 사용하고 있는 Huff의 4분위 방법의 누가우량백분율을 이용하여 통계 모델링에서 간결함의 원리에 따라 변수선택법을 이용하여 시간분포 회귀식을 유도하였으며, 유의성 검정을 통한 시간분포 회귀식의 검증을 실시하였다. 변수선택법과 유의성 검정을 통한 시간분포 회귀식 산정 결과 전진선택법과 후방제거법의 장점을 모두 가지고 있는 단계선택법을 이용하여 시간분포 회귀식을 유도하는 것이 가장 적합한 것으로 분석되었다.

• 환경생물
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• 제21권4호
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• pp.422-427
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• 2003

The spatio-temporal distribution of four coexisting acartiid species in two subgenera Acartiura (Acartia hongi and A. omorii) and Odontacartia (A. erythraea and A. pacifica) was examined at seven stations in the southwestern waters of Korea, between January to December 1998. A. hongi occurred dominantly in the northern regions from winter to spring while A. omorii predominated in the southern regions in spring and early summer when the more saline (> 33.0 psu) and high chlorophyll-$\alpha$ concentration water mass appeared. With the increase of temperature (> $20^{\circ}C$), however, both species disappeared and then replaced with A. erythraea and A. pacifica. A. erythraea (rare species), appeared in the middle regions where the high chlorophyll-$\alpha$ concentration ($3{\mu}g\; I^{-1}$) in the summer, while A. pacifica was abundant in all regions through summer and fall. It is suggested that the seasonal succession of the genus Acartia was subgenus-specifically affected by environmental factors such as temperature, salinity and chlorophyll-$\alpha$ concentration.

• Wind and Structures
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• 제5권5호
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• pp.441-462
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• 2002

This paper presents a practical numerical method to determine both the spatial and temporal distribution of driving rain on buildings. It is based on an existing numerical simulation technique and uses the building geometry and climatic data at the building site as input. The method is applied to determine the 3D spatial and temporal distribution of wind-driven rain on the facade a low-rise building of complex geometry. Distinct wetting patterns are found. The important causes giving rise to these particular patterns are identified : (1) sweeping of raindrops towards vertical building edges, (2) sweeping of raindrops towards top edges, (3) shelter effect by various roof overhang configurations. The comparison of the numerical results with full-scale measurements in both space and time for a number of on site recorded rain events shows the numerical method to yield accurate results.

• 한국통신학회논문지
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• 제21권5호
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• pp.1096-1108
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• 1996

In this paper, we propose a temporal adaptive tranform 3D SBC coder with motion compensation, exploiting redundancy in the temporal domain. We propose a temporal adaptivity measure, by which the R-D optimal temporal transform can be chaosen. The base temporal subband frame is coded using H.261-like MC-DCT coder, while the higher temporal subband frames are coded using the 2D adaptive wavelet packet bases, considering the various energy distribution which results from the temporal variation. In encoding the subbands, we employ adaptive scanning methods, uniform step-size quantization with VLC, and coded/not-coded flag reduction technique using the quadtree structure. From the simulation results, the proposed adaptive 3D subband coder shows about 0.29~3.14 dB gain over the H.261 and the fixed 3D subband coder techniques.

• Spatial Information Research
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• 제13권3호
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• pp.253-260
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• 2005

본 연구의 목적은 GIS기술을 이용하여 적조의 시공간적인 분포를 분석하는 것이다. 적조에 의해 발생하는 피해는 적조 생물종에 따라 다양하게 나타난다 때문에 적조의 피해를 저감하기 위해서는 시-공간적인 적조 생물종의 분포특성을 파악하는 것이 중요하다. 이러한 관점에서 우리는 최초의 적조발생지역, 공간적 발생빈도, 적조의 이동 등을 분석하였다. 본 연구에서 사용된 공간자료는 적조 속보 보고에 의해 공간분포를 디지타이징하였고, 적조데이터베이스를 구축하기 위해 적조 생물종, 생물 밀도, 수온 등의 다양한 속성자료를 구성하였다. 적조의 시-공간적 분포 특성을 분석하기 위해 다양한 공간분석기법을 적용하였다. 이러한 공간분석 결과로부터 남해에서의 시-공간 적이 적조 공간 정보를 얻을 수 있었다.