A Numerical Simulation on Red Tide Formation

Tetsuo Yanagi 한국해안해양공학회 1993 학술강연회 발표논문초록집 Vol.1 No.1

A STUDY OF SEASONAL VARIATION OF THE RESIDUAL FLOW AFTER SAEMANGEUM RECLAMATION BY A ROBUST DIAGNOSTIC AND PROGNOSTIC NUMERICAL MODEL

신문섭,Tetsuo Yanagi,Dinh Van Manh 한국해안해양공학회 1999 학술강연회 발표논문초록집 Vol.1 No.1

Saemangeum coastal area is being constructed the 33㎞ sea dike and 40,100㏊ reclamation area. The purpose of this study is to find the residual circulations in four seasons after the dike construction by a robust diagnostic and prognostic numerical model. Heat flux at the sea surface in January, May, August, October was adopted on the basis of the daily inflow of solar radiation at the earth surface, assuming an average atmospheric transmission and no clouds, as a function of latitude and time of year (George L.P.,J. E. William,1990). The discharge from the Geum, the Mankyung and the Dongjin Rivers was adopted on the basis of experience formula of river flow in January, May, August, October. Water temperature and salinity along the open boundaries are obtained from the results of field observations. Seasonal variation of the residual flow in the Saemangeum coastal area is investigated with use of a robust diagnostic numerical model. Residual flow was calculated diagnostically from the observed water temperature, salinity and wind data. Calculated residual flow field in the Saemangeum coastal area at the upper layer in spring formed clockwise circulation in the Saemangeum coastal area and an anti-clockwise circulation between Wi and Shinsi islands. The flow pattern at the upper layer during summer was from north to south. The flow pattern at the upper layer during autumn was clockwise circulation in the Saemangeum coastal area. The flow pattern at the middle layer during autumn was clockwise circulation around Wi island. The flow pattern at the middle layer was toward the mouths of the Dongjin and the Mankyung Rivers. We think that variation of flow pattern may be due to the change of river discharge.The flow pattern at the upper layer during winter was from north to south in the coastal region. On the basis of the caculated results of residual flow in winter(January) and summer(August), we think that the wind-driven current and density-driven current plays the most important role in the seasonal variation of residual flow in the Saemangeum coastal area. The results of seasonal variation of the residual flow in the Saemangeum coastal area by a prognostic numerical model lead to the following conclusions: Water temperature in spring is the highest, salinity is the lowest and density is the lowest at the upper layer near the coast after the dike construction. Water temperature in summer is the highest at the inner coastal area of the Geum River. Salinity is the lowest at the mouth of the Geum River in the upper layer. Water temperature in autumn is the highest at the mouth of the Geum River. Salinity is the lowest at the mouth of the Geum River in the upper layer, but increases to the 초록짤림

Mitigation in Saemangeum Bay

신문섭,Tetsuo Yanagi,Sung Kun Hong 한국해안해양공학회 1995 학술강연회 발표논문초록집 Vol.1 No.1

The reclamation area of Saemangeum(Kunsan) located between 126˚10´E -126˚50 E and 35˚35´N-36˚05´N the western coast of Korea. The constriction of the 33㎞ sea dike is building in the Saemangeum area. When the construction of the sea dike in the coastal region takes plase, there exists ,a certain amount of soil which is diffused by the tidal current. Behavior of the soil diffusion usually depends on its intrinsic characteristics, bathymetry, construction method and used machinery. The amount of soil at the construction acts as a pollutant which is the cause of changing the marine environment. When the soil material is diffused, it may form a layer which obstructs the light passing into the sea and causes the extinction or alteration of the living beings on the sea bottom. The settlement of soil material could change the sea bottom deposit. The purpose of MITIGATION is to harmonize the development and the conservation of enviroment, to restrict environmental destruction and to reproduce the enviroment damaged by the construction in the coastal region. The purpose of this study is to find the method by which we minimize the anti-function of development in the coastal region. Tide and tidal current are calculated using a two-dimensional numerical model before the construction of sea dike in Saemangeum Bay. The numerical results are compared well with field observations. On the basis of these results, we calculated the tide and tidal current after the construction of the sea dike in order to investigate the change of the tide and tidal current after the constriction of the sea dike. Moreover, we calculated the tide and tidal current after the construction of submerged breakwater in order to preserve the environmental condition of creature habitat. We compared the tide and tidal current before and after the construction of submerged breakwater, to investigate the possibility of MITIGATION in the fisheries.

Difference of Nutrients Budgets in the Bohai Sea between 1982 and 1992 related to the Decrease of the Yellow River Discharge

Hayashi, Mitsuru,Yanagi, Tetsuo,Xinyu, Guo The Korean Society of Oceanography 2004 Journal of the Korean Society of Oceanography Vol.39 No.1

Difference of Dissolved Inorganic Phosphorus (DIP), Dissolved Inorganic Nitrogen (DIN) and Dissolved Silicate (DSi) budgets in the Bohai Sea between 1982 and 1992 related the decrease of the Yellow River discharge is discussed on the basis of observed data. The estuarine circulation in the Bohai Sea had been weakened from 1982 to 1992 due to the decrease of the Yellow River discharge and the average residence time of fresh water had become longer. DIN concentration increased but DIP and DSi concentrations decreased from 1982 to 1992 in the Bohai Sea. Primary production was regulated mainly by water temperature and DIN concentration in 1982 but it was regulated mainly by DIP concentration in 1992. Primary production was larger than decomposition plus bottom release and nitrogen fixation was larger than denitrification in 1982. However, decomposition plus bottom release was larger than primary production and denitrification was larger than nitrogen fixation in 1992 in the Bohai Sea.

Difference of Nutrients Budgets in the Bohai Sea between 1982 and 1992 related to the Decrease of the Yellow River Discharge

Mitsuru Hayashi,Tetsuo Yanagi,Guo Xinyu 한국해양과학기술원 2004 Ocean science journal Vol.39 No.1

Difference of Dissolved Inorganic Phosphorus (DIP), Dissolved Inorganic Nitrogen (DIN) and Dissolved Silicate (DSi) budgets in the Bohai Sea between 1982 and 1992 related the decrease of the Yellow River discharge is discussed on the basis of observed data. The estuarine circulation in the Bohai Sea had been weakened from 1982 to 1992 due to the decrease of the Yellow River discharge and the average residence time of fresh water had become longer. DIN concentration increased but DIP and DSi concentrations decreased from 1982 to 1992 in the Bohai Sea. Primary production was regulated mainly by water temperature and DIN concentration in 1982 but it was regulated mainly by DIP concentration in 1992. Primary production was larger than decomposition plus bottom release and nitrogen fixation was larger than denitrification in 1982. However, decomposition plus bottom release was larger than primary production and denitrification was larger than nitrogen fixation in 1992 in the Bohai Sea.

A three dimensional numerical model of tide and tidal current in the bay of Cheonsu in Korea

Moon Seup Shin,Tetsuo Yanagi,Dinh-Van Manh,Soo Yong Ha 한국수자원학회 1998 한국수자원학회 학술대회 Vol.1998 No.1

Possible Prevention of Neonatal Death: A Regional Population-Based Study in Japan

Shigeki Koshida,Takahide Yanagi,Tetsuo Ono,Shunichiro Tsuji,Kentaro Takahashi 연세대학교의과대학 2016 Yonsei medical journal Vol.57 No.2

Purpose: The neonatal mortality rate in Japan has currently been at the lowest level in the world. However, it is unclear whether there are still some potentially preventable neonatal deaths. We, therefore, aimed to examine the backgrounds of neonatal death and the possibilities of prevention in a region of Japan. Materials and Methods: This is a population-based study of neonatal death in Shiga Prefecture of Japan. Results: The 103 neonatal deaths in our prefecture between 2007 and 2011 were included. After reviewing by a peer-review team, we classified the backgrounds of these neonatal deaths and analyzed end-of-life care approaches associated with prenatal diagnosis. Furthermore, we evaluated the possibilities of preventable neonatal death, suggesting specific recommendations for its prevention. We analyzed 102 (99%) of the neonatal deaths. Congenital malformations and extreme prematurity were the first and the second most common causes of death, respectively. More than half of the congenital abnormalities (59%) including malformationsand chromosome abnormality had been diagnosed before births. We had 22 neonates with non-intensive care including eighteen cases with congenital abnormality and four with extreme prematurity. Twenty three cases were judged to have had some possibility of prevention with one having had a strong possibility of prevention. Among specific recommendations of preventableneonatal death, more than half of them were for obstetricians. Conclusion: There is room to reduce neonatal deaths in Japan. Prevention of neonatal death requires grater prenatal care by obstetriciansbefore birth rather than improved neonatal care by neonatologists after birth.

A study of sedimentation prooesses in estuary of the Geum river before and after construction of Saemangeum the dike

Moon Seup Shin,Tetsuo Yanagi,Ick Joong Kim 대한토목학회 1998 대한토목학회 학술발표회 논문집 Vol.1998 No.3

Seasonal Variation of Kinetic and Potential Energy of Residual Flow Field in Suyoung Bay , Korea

Kim, Dong-Sun,Yanagi, Tetsuo 한국환경과학회 1997 한국환경과학회지 Vol.6 No.4

In order to study the seasonal variation of kinetic and potential energy of residual flow field in Suyoung Bay of Korea, we calculated its energy budget and compared it with the tidal energy there. The potential energy shows the large value in winter and spring and the small one in summer and early autumn when the density stratification is developed. The kinetic energy of residual flow varies seasonally and the seasonally averaged kinetic energy of residual flow per unit area is 6.4 × 10 exp (-4) ergs s^-1cm^-2. It is mainly governed by the density-driven current with the exception of that in November when the kinetic energy of tide-induced residual current is larger than those of density-driven current and winddriven current. An averaged fraction of the kinetic energy of tide-induced residual current, wind-driven current and density-driven current, which are the major components of residual flow, is 29.1%, 3.4%, 67.5%, respectively, to the kinetic energy of residual flow. The fraction of kinetic energy of residual flow, potential energy and tidal energy per unit area is 1.0 : 6.7 × 10 exp (3) : 8.2 × 10 exp (4), respectively.