scholarly journals PERFORMANCES OF THE RIP CURRENT WARNING SYSTEM AT THE HAEUNDAE COAST OF SOUTH KOREA

2018 ◽  
pp. 20
Author(s):  
Junwoo Choi ◽  
Sung-Bum Yoon ◽  
Jimin Ko ◽  
Tae-Soon Kang
Keyword(s):  
South Korea ◽  
Large Scale ◽  
Warning System ◽  
Wave Model ◽  
Weather Conditions ◽  
Wave Crest ◽  
Risk Level ◽  
Rip Current ◽  
Rip Currents ◽  
Incident Waves

Haeundae is one of the most beautiful beaches in Korea, and is also notorious for frequent and strong rip currents. Every recent year in this beach, hundreds of swimmers rescued from rip currents have been reported. The large-scale Haeundae rip current is known to be a kind of transient rip currents which is hardly predicted. The successive ends of wave-crest pattern (i.e., honeycomb wave-crest pattern(Dalrymple et al., 2011)), which generate rip current, are mainly formed by two-directional wave trains due to the refraction of incident swells over submerged shoals and ridges of the Haeundae coast. Many people are caught by the rip current in the relatively calm sea and weather conditions. The incident waves generating rip currents are nearly monochromatic with the wave period of 7-13 seconds. These swells are supposed to be generated by distant typhoons formed in the Philippine Sea. Some of them might propagate with dispersion and dissipation during the travel toward the south coast of the Korean Peninsula, especially to the Haeundae coast. In order to protect the swimmers from the rip current accidents, Choi et al. (2014) proposed a method for a rip current warning system, and Korea Hydrographic and Oceanographic Administration (KHOA) has established and operated the rip current warning system to the Haeundae beach. The rip current warning system estimates the rip current risk level based on the real-time incident wave conditions measured near the beach and the database pre-calculated by a numerical model according to various wave and tide conditions and the topography of the Haeundae coast. The Boussinesq wave model, FUNWAVE (Wei et al., 1999; Choi et al., 2015) was utilized for resolving the ends of the wave crests. This study showed the performance of the forecast and warning system of the rip current at the Haeundae coast of South Korea.

scholarly journals LABORATORY MODEL TEST OF TRANSIENT RIP CURRENTS DUE TO PSEUDO HONEYCOMB PATTERN WAVES

2018 ◽  
pp. 19
Author(s):  
Junwoo Choi ◽  
Min Roh ◽  
Hyung-sik Hwang
Keyword(s):  
Large Scale ◽  
Wave Pattern ◽  
Nodal Line ◽  
Generation Mechanism ◽  
Wave Crest ◽  
Laboratory Model ◽  
Rip Current ◽  
Rip Currents ◽  
Wave Trains ◽  
Honeycomb Pattern

The Haeundae coast of South Korea is famous for its beautiful beach, but the rip current, from which the beach-guards rescue more than 100 people every summer at the beach, is now a notorious phenomenon. The large-scale Haeundae rip current is known to be a transient rip current caused by multi-directional wave trains rather than the topography-induced rip current, for example, due to a gap of sandbar. In other words, the rip current seems develop along the cross-shore nodal line area in the honeycomb wave-crest pattern (Dalrymple et al., 2011) which are generated in a shallow water when two wave trains propagate with slightly different wave directions (i.e., interference pattern). The wave pattern is formed by the refraction of incident swells over submerged shoals and ridges of the Haeundae coast. The Haeundae rip current is an example explained by the vortex generation due to the ends of wave crests in Peregrine(1998), which is known of the basic generation mechanism of rip currents(Johnson and Pattiaratchi, 2006; Clark et al., 2012; Feddersen, 2014). To understand the generation mechanism and verify the numerical model results of the Haeundae rip current, the laboratory experiment was planned. This study showed the preliminary laboratory observations which include the pseudo honeycomb pattern of incident waves and its resultant rip current.

scholarly journals Surveying rip current survivors: preliminary insights into the experiences of being caught in rip currents

2012 ◽  
Vol 12 (4) ◽  
pp. 1201-1211 ◽  
Author(s):  
D. Drozdzewski ◽  
W. Shaw ◽  
D. Dominey-Howes ◽  
R. Brander ◽  
T. Walton ◽  
...  
Keyword(s):  
Large Scale ◽  
Current Knowledge ◽  
Swimming Ability ◽  
Rip Current ◽  
Rip Currents ◽  
Beach Safety ◽  
Demographic Groups ◽  
Safety Message ◽  
Informed Group ◽  
Safety Knowledge

Abstract. This paper begins a process of addressing a significant gap in knowledge about people's responses to being caught in rip currents. While rip currents are the primary hazard facing recreational ocean swimmers in Australia, debate exists about the best advice to give swimmers caught in rip currents. Such surf rescue advice – on what to do and how to respond when caught in a rip – relies on empirical evidence. However, at present, knowledge about swimmers reactions and responses to rip currents is limited. This gap is a considerable barrier to providing effective advice to beach goers and to understanding how this advice is utilised (or not) when actually caught in the rip current. This paper reports the findings of a pilot study that focussed on garnering a better understanding of swimmers' experiences when caught in rip currents. A large scale questionnaire survey instrument generated data about rip current survivors' demographics, knowledge of beach safety and their reactions and responses when caught in a rip current. A mix of online and paper surveys produced a total of 671 completed surveys. Respondents were predominantly an informed group in terms of rip current knowledge, beach experience and had a high self-rated swimming ability. Preliminary insights from the survey show that most respondents recalled a "swim across the rip/parallel to the beach" message when caught in the rip and most escaped unassisted by acting on this message. However, while nearly a quarter of respondents recalled a message of "not to panic", short answer responses revealed that the onset of panic inhibited some respondents from recalling or enacting any other type of beach safety message when caught in the rip current. Results also showed that despite the research sample being younger, competent and frequent ocean swimmers, they were more likely to swim at unpatrolled beaches and outside of the red and yellow safety flags. Moreover, they were still caught in a rip current and they panicked. The findings of this study have significant implications for a range of demographic groups of differing beach safety knowledge and swimming ability who may be caught in rip currents behave, we know very little about how beach goers may respond to being caught in them.

EPIGONE: the argus on the daily operation of throttle structures

2013 ◽  
Vol 8 (3-4) ◽  
pp. 382-389 ◽  
Author(s):  
G. Dirckx ◽  
T. Wambecq ◽  
A. Qvick ◽  
M. Weemaes
Keyword(s):  
Water Level ◽  
Large Scale ◽  
Warning System ◽  
Cost Effective ◽  
Weather Conditions ◽  
Radar Data ◽  
Text Messages ◽  
Central Controller ◽  
Level Data ◽  
Set Up

This study presents the development of an Early Warning System (EWS) called EPIGONE focusing on the detection of dry weather overflows in the vicinity of throttle structures in sewer systems. Throttle structures are considered as vital parts of a sewer system as they are control sections limiting flow rates to a designed operational value. Because these structures are by definition prone to potential clogging or blockages, a close follow-up of the daily operation by an EWS facilitates increased vigilance or even alarm. Primary goal of EPIGONE is to alert operators and thus allow fast intervention in case of suspected failures of these structures within a settled timeframe. EPIGONE combines overflow water level measurements with rainfall radar information to determine Combined Sewer Overflow (CSO) activity during dry weather as this dual condition will indicate malfunctioning. This combination of measurements was found to be the most cost effective set-up to deploy on a large scale. Water level data are recorded and logged on-site and sent to a central controller via GSM/GPRS, where an algorithm determines dry weather overflow conditions. Rainfall radar data are used as criterion to decide on dry weather conditions. From there on alarms are sent out to multiple recipients via e-mail and/or text messages (SMS). Next to this, it is obvious that this system can also be used for ‘regular’ wet weather CSO monitoring.

scholarly journals A FIELD AND NUMERICAL STUDY INTO RIP CURRENTS IN WIND-SEA DOMINATED ENVIRONMENTS

2012 ◽  
Vol 1 (33) ◽  
pp. 36
Author(s):  
Gundula Winter ◽  
Ap Van Dongeren ◽  
Matthieu De Schipper ◽  
Jaap Van Thiel de Vries
Keyword(s):  
Surf Zone ◽  
Numerical Study ◽  
Warning System ◽  
Rip Current ◽  
Rip Currents ◽  
Mean Flow ◽  
Flow Properties ◽  
Wind Sea ◽  
Wave Induced ◽  
Made In

Rip currents are wave-induced and off-shore directed flows which occur frequently in the surf zone and can pose a serious threat to swimmers. While the behaviour of rip currents has been studied in swell-dominated environments, less is known about their characteristics in wind-sea dominated environments. This study aims to improve the knowledge on rip currents in these environments such as the Dutch coast. In a field campaign at Egmond aan Zee (The Netherlands), Lagrangian velocities in the surf zone were measured with drifter floats. An extensive dataset of rip current measurements was collected from which parameters that initiate rip currents and affect their mean flow properties were identified. Numerical simulations with XBeach aided to understand and confirm the observations made in the field. A reduction of the hydrodynamic parameters along with simplification of the bathymetry in the model allowed for identification of the governing rip current parameters, which can be the basis for a warning system.

Optimizing genotype-environment-management interactions to ensure silage maize production in the Chinese Maize Belt

2020 ◽  
Vol 80 (2) ◽  
pp. 133-146
Author(s):  
L Zhang ◽  
Z Zhang ◽  
J Cao ◽  
Y Luo ◽  
Z Li
Keyword(s):  
Field Experiments ◽  
Weather Conditions ◽  
Growth Cycle ◽  
High Energy ◽  
Risk Level ◽  
Energy Yield ◽  
Maize Production ◽  
Early Date ◽  
Environment Management ◽  
Silage Maize

Grain maize production exceeds the demand for grain maize in China. Methods for harvesting good-quality silage maize urgently need a theoretical basis and reference data in order to ensure its benefits to farmers. However, research on silage maize is limited, and very few studies have focused on its energetic value and quality. Here, we calibrated the CERES-Maize model for 24 cultivars with 93 field experiments and then performed a long-term (1980-2017) simulation to optimize genotype-environment-management (G-E-M) interactions in the 4 main agroecological zones across China. We found that CERES-Maize could reproduce the growth and development of maize well under various management and weather conditions with a phenology bias of <5 d and biomass relative root mean square error values of <5%. The simulated results showed that sowing long-growth-cycle cultivars approximately 10 d in advance could yield good-quality silage. The optimal sowing dates (from late May to July) and harvest dates (from early October to mid-November) gradually became later from north to south. A high-energy yield was expected when sowing at an early date and/or with late-maturing cultivars. We found that Northeast China and the North China Plain were potential silage maize growing areas, although these areas experienced a medium or even high frost risk. Southwestern maize experienced a low risk level, but the low soil fertility limited the attainable yield. The results of this paper provide information for designing an optimal G×E×M strategy to ensure silage maize production in the Chinese Maize Belt.

scholarly journals Assessment of Numerical Methods for Plunging Breaking Wave Predictions

2021 ◽  
Vol 9 (3) ◽  
pp. 264
Author(s):  
Shanti Bhushan ◽  
Oumnia El Fajri ◽  
Graham Hubbard ◽  
Bradley Chambers ◽  
Christopher Kees
Keyword(s):  
Solitary Wave ◽  
Wave Breaking ◽  
Large Scale ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Wave Crest ◽  
Breaking Wave ◽  
Rans Turbulence Models ◽  
Run Up ◽  
Better Than

This study evaluates the capability of Navier–Stokes solvers in predicting forward and backward plunging breaking, including assessment of the effect of grid resolution, turbulence model, and VoF, CLSVoF interface models on predictions. For this purpose, 2D simulations are performed for four test cases: dam break, solitary wave run up on a slope, flow over a submerged bump, and solitary wave over a submerged rectangular obstacle. Plunging wave breaking involves high wave crest, plunger formation, and splash up, followed by second plunger, and chaotic water motions. Coarser grids reasonably predict the wave breaking features, but finer grids are required for accurate prediction of the splash up events. However, instabilities are triggered at the air–water interface (primarily for the air flow) on very fine grids, which induces surface peel-off or kinks and roll-up of the plunger tips. Reynolds averaged Navier–Stokes (RANS) turbulence models result in high eddy-viscosity in the air–water region which decays the fluid momentum and adversely affects the predictions. Both VoF and CLSVoF methods predict the large-scale plunging breaking characteristics well; however, they vary in the prediction of the finer details. The CLSVoF solver predicts the splash-up event and secondary plunger better than the VoF solver; however, the latter predicts the plunger shape better than the former for the solitary wave run-up on a slope case.

scholarly journals Benign Convulsions with Mild Rotavirus and Norovirus Gastroenteritis: Nationwide Data from the Health Insurance Review and Assessment Service in South Korea

Children ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 263
Author(s):  
Dong Hyun Kim ◽  
Dong Jun Ha ◽  
Yeong Seok Lee ◽  
Min Jun Chun ◽  
Young Se Kwon
Keyword(s):  
Health Insurance ◽  
South Korea ◽  
Large Scale ◽  
Rotavirus Vaccine ◽  
Annual Increase ◽  
Rotavirus Vaccination ◽  
Rotavirus Gastroenteritis ◽  
Norovirus Gastroenteritis ◽  
Increasing Trend

There have been no large-scale studies on the epidemiology of benign convulsions with mild gastroenteritis (CwG) since the introduction of the rotavirus vaccine in South Korea in 2007. This study aimed to analyze the trends in rotavirus gastroenteritis (RVGE) and rotavirus-associated CwG (RaCwG) after rotavirus vaccination. Further, we aimed to analyze changes in norovirus gastroenteritis (NVGE) and norovirus-associated CwG (NaCwG) using nationwide data from the Korean Health Insurance Review and Assessment Service. Between 2007 and 2019, this study analyzed children aged <6 years who were diagnosed with RVGE, NVGE, RaCwG and NaCwG. The changes in the prevalence of each disease and the ratio of CwG to enteritis were analyzed and the effects of age, sex and season were also analyzed. RVGE, RaCwG, NVGE and NaCwG were diagnosed in 273,898, 4246, 35,593 and 337 patients, respectively. The prevalence of RVGE was on a decreasing trend every year, but the prevalence of NaCwG and NVGE was on an increasing trend. There was a significant annual increase in the ratio of CwG to enteritis in both viruses. In order to control the prevalence of RaCwG, measures other than the rotavirus vaccine are required and measures to prevent norovirus are necessary.

scholarly journals Performance of Strawberry Varieties Developed for Perennial Matted-Row Production in Annual Plasticulture in a Cold Climate Region

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1407
Author(s):  
Courtney A. Weber
Keyword(s):  
Large Scale ◽  
Fruit Size ◽  
Weather Conditions ◽  
Cold Climate ◽  
Annual Production ◽  
High Yield ◽  
Production Cycle ◽  
Late Season ◽  
Berry Weight ◽  
High Yields

Annual plasticulture production of strawberries promises superior weed control, fruit quality and yields. However, strawberry varieties adapted for perennial, matted-row production and local markets in cold climate regions have not been widely tested for adaptation to an annual production cycle. Productivity of seven short-day varieties developed for matted-row and/or annual production was examined in an annual plasticulture system in two consecutive trials in central NY (lat. 42.87° N, long. 76.99° W) harvested in 2013 and 2014. ‘Flavorfest’ demonstrated good performance in Trial 1 with high yield (390 g/plant) and large fruit size (13.9 g mean berry weight). ‘Jewel’ was shown to be well adapted to the annual plasticulture system with consistently high yields (330 and 390 g/plant) that equaled or surpassed other varieties and had moderate fruit size. ‘Chandler’ performed similarly to previous trials conducted in warmer regions with yield (340 g/plant) and fruit size (9.8 g mean berry weight) similar to ‘Jewel’. ‘Clancy’ yielded less but was consistent from year to year. The late season varieties Seneca and Ovation showed marked variability between years, possibly due to drastically different temperatures during flowering and fruit development in Trial 1 compared to Trial 2. High temperatures in Trial 1 likely caused higher early fruit yield, a compressed season and a precipitous decline in fruit size in the later season, thus reducing yield in the late season. Survival after a second dormant period was poor resulting in a small second harvest and reduced fruit size. Overall, the system demonstrated many of the expected benefits but may be more sensitive to weather conditions in the region. While many varieties developed for matted-row production may work well in an annual plasticulture system, not all varieties are equally adapted. Performance of each variety should be determined independently before large scale adoption by growers.

scholarly journals The Relationships among Self-Worth Contingency on Others’ Approval, Appearance Comparisons on Facebook, and Adolescent Girls’ Body Esteem: A Cross-Cultural Study

2021 ◽  
Vol 18 (3) ◽  
pp. 901 ◽  
Author(s):  
Michael Prieler ◽  
Jounghwa Choi ◽  
Hye Eun Lee
Keyword(s):  
South Korea ◽  
Cultural Context ◽  
Large Scale ◽  
Body Esteem ◽  
Asian Country ◽  
Cross Cultural ◽  
European Countries ◽  
Self Worth ◽  
Appearance Comparison

The present study examined the relationship between appearance-related social comparison on social networking services (SNSs) and body esteem in a cross-cultural context (three European countries, i.e., Austria, Belgium, and Spain, versus one Asian country, i.e., South Korea). The role of self-worth contingency on others’ approval was considered to be a psychological and cultural factor. Utilizing a large-scale cross-national survey of early and middle adolescents in 2017, the responses of female adolescents (N = 981) were analyzed. The results generally support the findings from previous studies but also reveal cultural differences. Appearance comparison on Facebook negatively influenced girls’ body esteem in all European countries, but not in South Korea. Self-worth contingency on others’ approval negatively influenced girls’ body esteem across all four countries. Finally, a positive relationship between self-worth contingency on others’ approval and appearance comparison on Facebook was found in all European countries, but not among Korean girls. These findings suggest the importance of self-worth contingency on others’ approval and cultural contexts can be used to study the effects of body image-related SNS use.

Sign in / Sign up

Export Citation Format

Share Document