• 대한원격탐사학회지
• /
• 제38권5_2호
• /
• pp.707-723
• /
• 2022

위성기반 해수면온도는 광역 모니터링이 가능한 장점이 있지만, 다양한 환경적 그리고 기계적 이유로 인한 시공간적 자료공백이 발생한다. 자료공백으로 인한 활용성의 한계가 있으므로, 공백이 없는 자료 생산이 필수적이다. 따라서 본 연구에서는 한반도 주변 해역에 대해 극궤도와 정지궤도 위성에서 생산되는 해수면온도 자료를 두 단계의 기계학습을 통해 융합하여 4 km의 공간해상도를 가지는 일별 해수면온도 합성장을 만들었다. 첫번째 복원 단계에서는 Data INterpolate Convolutional AutoEncoder (DINCAE) 모델을 이용하여 다종 위성기반 해수면온도 자료를 합성하여 복원하였고, 두번째 보정 단계에서는 복원된 해수면온도 자료를 현장관측자료에 맞춰 Light Gradient Boosting Machine (LGBM) 모델로 학습시켜 최종적인 일별 해수면온도 합성장을 만들었다. 개발된 모델의 검증을 위해 복원 단계에서 무작위 50일의 자료 중 일부분을 제거하여 복원한 뒤 제거된 영역에 대해 검증하였으며, 보정 단계에서는 Leave One Year Out Cross Validation (LOYOCV) 기법을 이용하여 현장자료와의 정확도를 검증하였다. DINCAE 모델의 해수면온도 복원 결과는 상당히 높은 정확도(R²=0.98, bias=0.27℃, RMSE=0.97℃, MAE=0.73℃)를 보였다. 두번째 단계의 LGBM 보정 모델의 정확도 개선은 표층 뜰개 부이와 계류형 부이 현장자료와의 비교에서 모두 상당한 향상(RMSE=∆0.21-0.29℃, rRMSE=∆0.91-1.65%, MAE=∆0.17-0.24℃)을 보여주었다. 특히, 모든 현장 자료를 이용한 보정 모델의 표층 뜰개 부이와의 정확도는 동일한 현장 자료가 동화된 기존 해수면온도 합성장보다 나은 정확도를 보였다. 또한 LGBM 보정 모델은 랜덤포레스트(random forest)를 사용한 선행연구에서 보고된 과적합의 문제를 상당부분 해결하였다. 보정된 해수면온도는 기존의 초고해상도 해수면온도 합성장들과 유사한 수준으로 수온 전선과 와동 등의 중규모 해양현상을 뚜렷하게 모의하였다. 본 연구는 다종위성 자료와 기계학습 기법을 사용해 시공간적 공백 없는 고해상도 해수면온도 합성장 제작 방법을 제시하였다는 점에서 가치가 있다.

• 생태와환경
• /
• 제51권1호
• /
• pp.1-15
• /
• 2018

With land-use (cover) and water quality, the distributional characteristics of epilithic diatom communities were studied with 193 samples from estuaries of Korean peninsula between 2015 and 2016. Of total 394 taxa classified, Nitzschia perminuta (19.6%) and N. inconspicua (14.0%) were the 1st and 2nd dominant species. Using a cluster analysis, the epilithic diatom communities of Korean estuaries were divided into four groups (G1-G4). Ecological characteristics of each group were followed: G1 was located in estuaries of the East Sea, and characterized by high forest land-use and high DO and low nutrients; G2 was the eastern part of the South Sea, and characterized by low turbidity and nutrients; G3 was the western part of the South Sea, and characterized by high agriculture, low electric conductivity and low salinity; G4 was the Yellow Sea, and characterized by high nutrients. The environmental factors having significant correlation with diatom distributions were as follows: TN to G1, turbidity to G2, agriculture to G3, and TP to G4. Moreover, the important factors affecting the occurrence of indicator species were forest land-use for Fragilaria construens var. venter in G1, turbidity for Rhoicosphenia abbreviata in G2, urban land- use and total phosphorus (TP) for Bacillaria paradoxa and Hantzschia amphioxys of G3, and TP and turbidity for N. ovalis and Stephanodiscus invistatus of G4. These results collectively indicate that the distribution of epilithic diatom communities in Korean peninsula was largely effected by water quality and land cover/use.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제5권4호
• /
• pp.569-579
• /
• 2013

A steel-type breakwater that uses a submerged dual horizontal porous plate was originally proposed by Kweon et al. (2005), and its hydrodynamic characteristics and design methodology were investigated in a series of subsequent researches. In particular, Kweon et al. (2011) proposed a method of estimating the vertical uplift force that acts on the horizontal plate, applicable to the design of the pile uplift drag force. However, the difference between the method proposed by Kweon et al. (2011), and the wave force measured at a different time without a phase difference, have not yet been clearly analyzed. In this study, such difference according to the method of estimating the wave force was analyzed, by measuring the wave pressure acting on a breakwater model. The hydraulic model test was conducted in a two-dimensional wave flume of 60.0 m length, 1.5 m height and 1.0 m width. The steepness range of the selected waves is 0.01~0.03, with regular and random signals. 20 pressure gauges were used for the measurement. The analysis results showed that the wave force estimate in the method of Kweon et al. (2011) was smaller than the wave force calculated from the maximum pressure at individual points, under a random wave action. Meanwhile, the method of Goda (1974) that was applied to the horizontal plate produced a smaller wave force, than the method of Kweon et al. (2011). The method of Kweon (2011) was already verified in the real sea test of Kweon et al. (2012), where the safety factor of the pile uplift force was found to be greater than 2.0. Based on these results, it was concluded that the method of estimating the wave force by Kweon et al. (2011) can be satisfactorily used for estimating the uplift force of a pile.

• 한국양식학회지
• /
• 제17권1호
• /
• pp.12-23
• /
• 2004

Genomic DNAs were extracted from the muscle of twenty-two specimens of two shortnecked clam, Ruditapes phifippinarum populations collected in Anmyeondo and Seocheon. Genetic differences within and between populations were analysed by random amplified polymorphic DNAs-polymerase chain reaction (RAPD-PCR) using twenty arbitrary decamer primers. Out of 20 primers, 6 generated a total of 1,111 major and minor RAPD bands from individuals of two sites, producing approximately 4.2 average polymorphic bands per primer in individuals from Anmyeondo and ranging in size from less than 50 to larger than 1,500 base pairs (bp). The electrophoretic analysis of RAPD products amplified showed moderate levels of similarity among the different individuals in Seo-cheon population. The average bandsharing values (BS value) of the samples within population from Anmyeondo ranged from 0.155 to 0.684, whereas it was 0.143∼0.782 within population from Seocheon. The average BS value between individuals No. 13 and No. 14 from Seocheon was 0.782 which was higher than that of those from Anmyeondo. The single linkage dendrogram resulted from three primers (OPA-08, -09 and -20), indicating six genetic groupings composed of group 1 (No.4, 8 and 10), group 2 (No. 18), group 3 (No.2, 5 and 7), group 4 (No. 1, 3, 6, 9, 11, 12, 13, 14, 15 and 17), group 5 (16, 19 and 20) and group 6 (No. 21 and 22). In the Seocheon population, the individual No. 18 clustered distinctly from the others of this population. The observed genetic distance between the two populations from Anmyeondo and Seocheon was more than 0.209 (0.247 and 0.275). The shortest genetic distance (0.094) displaying significant molecular differences was between individuals No. 13 and No. 14. Especially, the genetic distance between individuals No. 22 and the remnants among individuals in two geographical populations was highest (0.275). This result illustrated that individual No.22 is distinct from other individuals within two shortnecked populations. The different geographical features of two sites may have caused the genetic diversity in two shortnecked clam populations.

• 대한토목학회논문집
• /
• 제28권4B호
• /
• pp.421-428
• /
• 2008

최근 들어 우리나라 전해역에 걸쳐 발생하고 있는 침식은 사회적인 문제가 되어왔다. 하지만, 해안구조물에 의한 기존의 방법으로 해안선을 보호하는 것이 "파랑장에 친화적인가?"라는 관점에서 개선의 여지가 있다. 새로운 형식의 철재형 이안제는 권혁민 등(2007)에 의해 제안되었다. 본 형식은 다수의 파일과 상부에 파랑진행방향과 수평으로 설치된 소파장치로 구성되어 있다. 본 형식은 해수유통원활, 대수심 축조수월, 공기단축 등의 장점이 있다. 본 연구는 소파제로서 철재형 이안제의 상부에 거치가 가능한 이열 조합판의 투과율을 실험적으로 평가했다. 일방향 불규칙파 시스템에 의한 모형실험을 통하여 반사율, 소파율, 투과율에 관하여 분석했다. 실험결과, 파형경사가 클수록 그리고 조합판의 폭-파장비가 클수록 투과율이 작아짐을 보였다. 본 연구는 이열 소파판 조합에 대하여 투과율 산정을 위한 직선식을 제안했다.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권10호
• /
• pp.1360-1365
• /
• 2004

Using the method of 'random sampling in typical colonies of the central area of the habitat', 60 Small-tailed Han sheep were obtained in Jining city, Shangdong province. The variations of Small-tailed Han sheep at 12 structural loci encoding blood proteins were detected by several electrophoresis techniques and their gene frequencies were then estimated. The same data of four other sheep populations from Near-sea Mainland in East Asia were cited for the analysis of genetic differentiation. The average heterozygosities of five populations, namely Kharkhorin sheep, Ulaanbaatar sheep, Small-tailed Han sheep, Hu sheep and Cham Tribe sheep were 0.3447, 0.3285, 0.3157, 0.3884 and 0.2300, respectively. The coefficient of gene differentiation among four populations, Kharkhorin sheep, Ulaanbaatar sheep, Small-tailed Han sheep and Hu sheep, was 0.045557, and that between these four breeds and Cham Tribe sheep was 0.088005, indicating that the level of gene differentiation among the former four sheep populations of Mongolian group was comparatively lower than that between Cham Tribe sheep and other four sheep populations. The origin of Cham Tribe sheep deserve further research. The documentary research on the evolution of Small-tailed Han sheep and Hu sheep from Mongolian sheep was further verified by the biochemical experiments in the study. It was reasonably deduced that Hu sheep, Small Tailed Han sheep and Cham Tribe sheep were decreasingly influenced by the bloodline of Mongolian sheep.

• 한국항해학회지
• /
• 제12권1호
• /
• pp.71-84
• /
• 1988

For traffic proceeding in random directions on a plane surface the frequency of collision, if no avoiding action in taken ,is approximately proportional to the square of the traffic density and directly proportional to the size and speed of the ship, Avoiding is normally taken and the rte of collisions is therefore also governed by additional factors such as the visibility, the effectiveness of the collisionavoidance rules, the competence of personnel or watchkeeping attitude, the maneuverability of the ship and the efficiency of radar and other equipments. From the viewpoint of watchkeeper who is responsible for maneuvering, watchkeeping attitude such as lookout and action to avoid collision is the most controllable factor among those mentioned above. In practice, according to the investigation of the institution of marine courts, about 50% co collisions occurred is caused by disorbedience to steering and sailing rules of international regulations for preventing collision at sea including lookout. So we classify the process of collisions with first sight of another ship , assessment of risk of collisions and action to avoid collisions and make a factural survey about lookout and action to avoid collisions from the point on "time" and " distance", namely relationship among ship's size, speed, first sight time of another ship, action to avoid collisions ,and distance from sight of another ship to collision occurred. According to the results of the actual survey , we come to conclude that most of collisions occurred are due to improper lookout and ineffective action to avoid collision which means time lag from first sight of another ship to time of action taken to avoid collision is relatively long. is relatively long.

• Ocean and Polar Research
• /
• 제25권4호
• /
• pp.653-662
• /
• 2003

Changes in the area of geo-ecosystem $(62^{\circ}09'S,\;58^{\circ}31'w)$ reflect climatic changes in the South Shetland Islands. Air temperature and deglaciation will increase. The ice-free space area at the SSSS 8- (ASPA 121) site has enlarged threefold during the last 21 years, thus creating conditions for inhabitation and succession. Wind, water and snow play important roles in transportation of geochemical components. They distribute nutrients, mineral substances, seeds, fragments of plants and animals, etc. Plant and animal colonization is patchy and it happens at random in an 'island' - like manner. The colonization pattern is dependant, to a high degree on physical factors. The newly uncovered ice-free areas are at first inhabited by a vascular plant known as the Deschampsia antarctica. The border of the land-oasis with Admiralty Bay is the place where the processes related to animal feeding at the sea and reproduction on the land take place. Bird colonies and pinniped lairs form centers of fertilization surrounded by high chemical gradients dependent on the direction of the flow of nutrients $(e.g.\;NH_4)$. During the last 25 years, the numbers of penguins in this region have decreased, and thus the amount of materials excreted on land has diminished. The numbers of fur seals change in multi-annual cycles, and their migration into this area is related to the E1 $Ni\~{n}o$ phenomenon. The numbers of elephant seals in the area did not change. Organic matter deposited by the sea onto the shore are a source of nutrients and deficient chemical elements on land. Mineral matter is washed out into the waters of Admiralty Bay. These processes change seasonally, and multi annually. Negative effects on the environment at Arctowski Station induced by man are slight, but noticeable nevertheless. Physical processes have the largest influence on the living conditions and distribution of plants and animals, and as a consequence, on the functioning of the geo-ecosystem in the coastal-shore zone of the Maritime Antarctic.

• 생명과학회지
• /
• 제14권1호
• /
• pp.32-37
• /
• 2004

ITS2 부위를 시퀀싱하여 Pseudo-nitzschia delcatissima, P. multiseries, P. pungens, P. subfraudulenta 상호간의 유전자 다양도를 조사함과 아울러 RAPD-PCR pattern을 이용하여 유사도를 구하였다. 유전자 거리를 근거로 했을 때 P. delicatissima 종은 P. multiseries와 P. pungens와는 유전적 거리가 상당히 요원하였고, 심지어 P. subfraudenlta와도 거리를 보였다. 유사도의 경 P. multiseries와 P. pungens는 0.31로 보인 반면에, P delicatissima는 다른 세종과 0.81를 나타내었다. 따라서 P. delicatissima 종은 P. multiseries, P. pungens, P. subfraudulenta와는 유전적으로 밀접하지 않는 관계로 보였다. ITS2부위는 Pseudo-nitzschia 동정에 사용될 수 있는 유용한 도구로 보이며 형태적으로 구분할 수 없는 P. multiseries와 P. pungens을 구분할 수 있다. 또한 RAPD-PCR 방법도 단시간에 Pseudo-nitzchia을 분리시키는데 사용될 것으로 보인다.

• 수산해양교육연구
• /
• 제23권3호
• /
• pp.477-485
• /
• 2011

For the identifying of spatial distribution pattern, Moran's Index(I) which has the range of values from -1 to +1 is common method for the spatial autocorrelation measurement. When I is close to 1, all neighboring features have close to the same value, indicating clustered pattern. Conversely, if the spatial pattern is dispersed, I is close to -1. And I closing to 0 means spatially random pattern. However, this index equation is influenced by how defining the neighboring features for target feature. To compare and understand the difference of neighborhood definition methods, fixed distance neighboring method and Gabriel Network method were used for I. In this study, these two methods were applied to two marine environments with water quality data. One is Gwangyang Bay which has complex geometric coastal structure located in South Sea of Korea. Another is Uljin area adjacent to open sea located in east coast of Korea. The distances between water quality observed locations were relatively regular in Gwangyang Bay, however, irregular in Uljin area. And for the fixed distance method popular Arc GIS tool was used, but, for the Gabriel Network, Visual Basic program was developed to produce Gabriel Network and calculate Moran's I and its Z-score automatically. According to this experimental results, different spatial pattern was showed differently for some data with using of neighboring definition methods. Therefore there is need to choose neighboring definition method carefully for spatial pattern analysis.