• Journal of Korea Port Economic Association
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• v.32 no.1
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• pp.179-192
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• 2016

This purpose of this study is to identify the Analysis of Safety Control Factor Influenced on the Management of the Costal Shipping Companies. The study selected the analysis of safety control factors performed the Brain-Storming method, Depth Interview and Face-to-Face Interview. This survey targets are 25 experts for the opinions of expert groups with CEO of coastal shipping companies. This study used ISM(Interpretive Structural Modeling)to analyze the safety control factors and understand correlations between factors and found that sufficient acquirement of legal shipping equipment and freight (or passenger) management factors are the safety control factors that give the biggest effect on the management of coastal shipping companies. ISM analysis results are as follows. The factors that most influence the advancement of safety management is ensured the legal faithful to ship equipment. In the future, a survey have to multiple targets and to improve the practical needs by using a FSM (Structural Fuzzy Modelling).

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.30 no.6
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• pp.326-336
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• 2018

Continuous measurement of nearshore waves around Korea over long period is very demanding to setup plans for prevention of disasters of port and coastal structures. In this respect, a new web-based system, termed as WINK, was established, which collects nearshore wave data from Korea Meteorological Agency (KMA), Korea Hydrographic and Oceanographic Agency (KHOA), and Ministry of Oceans and Fisheries (MOF) and provide them after quality control of the data. This paper describes technical aspects regarding collection and selection of the wave observation data, construction of wave hindcasting data, the methodology of quality control for the selected wave data, and overall process of building the web-based data providing system.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.31 no.1
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• pp.1-8
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• 2019

This research mainly focuses on examining the applicability of the deterministic model SLOSH (Sea, Lake and Overland Surges from Hurricanes) on Seas covering South Korea. Also, a simple bathtub approach which estimates coastal inundation area is validated as a first step of estimating effects of sea-level rise on the coastal cities of South Korea according to climate change. Firstly, the typhoon-induced surges are obtained from the model SLOSH by adopting historical typhoons MAEMI (0314) and BOLAVEN (1215). The results are compared to observational, typhoon-induced surge heights at several tidal stations. The coastal inundation area is estimated by comparing the maximum envelop of waves (MEOW) and the elevation of coastal land. It reproduces well the inundation area. It can be seen that this research gained applicability for estimating further potential coastal inundation with climate changes.

• Journal of Coastal Disaster Prevention
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• v.4 no.4
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• pp.189-196
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• 2017

Ocean Research Stations (ORSs) is the ocean platform type observation towers and measured oceanic, atmospheric and environmental data. These station located on the offshore area far from the coast, so they can produce the data without land effect. This study focused to improve the wave data quality of ORS station. The wave observations at ORSs are used by the C-band (5.8 GHz, 5.17 cm) MIROS Wave and Current Radar (MWR). MWR is convenient to maintenance and produce reliability wave data under bad weather conditions. MWR measured significant wave height, peak wave period, peak wave direction and 2D wave spectrum, so it's can provide wave information for researchers and engineers. In order to improve the reliability of MWR wave data, Datawell Waverider Buoy was installed near the one ORS (Socheoncho station) during 7 months and validate the wave data of MWR. This study found that the wave radar tend to be overestimate the low wave height under wind condition. Firstly, this study carried out the wave Quality Control (QC) using wind data, however the quality of wave data was limited. So, this study applied the four filters (Correlation Check, Direction Filter, Reduce White Noise and Phillips Check) of MWR operating software and find that the filters effectively improve the wave data quality. After applying 3 effective filters in combination, the RMSE of significant wave height decreased from 0.81m to 0.23m, by 0.58m and Correlation increased from 0.66 to 0.96, by 0.32, so the reliability of MWR significant wave height was significantly improved.

• Journal of Coastal Disaster Prevention
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• v.4 no.3
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• pp.111-118
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• 2017

In this study, pull box members were designed by finite element analysis of a steel plate covering a pull box to secure its safety on the landing pier dedicated to the large research survey ship. It was assumed that the maximum load is due to the 250 tonf class crane used for unloading work when the working environment in the upper part of the landing pier was considered. The safety of the pull box was evaluated by the comparison between the yield strength of the steel plate and the result of stress analysis on the steel plate due to the crane load. It was found that the stress at the plate from the crane load exceeded the yield strength of the steel(205MPa) when the upper part of the pull box was protected by a $1950{\times}1950mm$ steel plate cover. In order to compensate for this, a concrete filled steel tube(CFT) column with a diameter of 150 mm and a steel thickness of 10 mm was reinforced at the center of the plate, and the finite element analysis was carried out. However, the maximum stress at the steel plate was higher than the yield strength of the steel in some load cases so that it was tried to find appropriate thickness of the steel plate and diameter of the CFT columns. Finally, the analysis results showed that the safety of the pull box was secured when the thickness of the steel plate and the diameter of the CFT column were increased to 30mm and 180mm, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.273-273
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• 2022

혼합층(Mixed layer)은 온도가 일정한 수심층으로, 해수표면에 작용하는 바람의 영향으로 인하여 해수가 위아래로 섞여 형성된다. 이러한 혼합층은 영양염의 순환과 산소의 공급 등과 함께 일차생산량을 결정하는 중요한 요인이 될 수 있으며 혼합층 두께의 변동은 양식 산업에 영향을 미칠 수 있다. 최근에는 기후변화로 인한 해수면 상승 및 해수온 상승 등이 지속되고 있으며, 이러한 현상은 해양생태계의 변화를 초래하여 수산업의 피해를 유발할 수 있다(강원연구원, 2017). 이에 국립수산과학원, 기상청, 국립해양조사원 등 유관기관에서는 정선해양 수온 관측 및 해수순환모델을 이용하여 혼합층의 분석을 수행하고 있으나 격자 구축 및 초기·경계장 설정의 한계가 존재하여 정밀하고 정확한 혼합층 분석에는 어려움이 있다. 이에 본 연구에서는 비정형격자를 사용하여 격자 구축에 제약이 없는 SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model)을 이용하여 우리나라 연안해역의 계절변화 및 기후변동성에 따른 혼합층 두께의 변화를 검토하고자 한다. 연구대상지는 서해·동해·남해를 포함한 우리나라 전체 연안 해역(위도: 32°N ~ 39°N, 경도: 124°E ~ 132°E)으로 선정하였으며, 격자크기 100 ~ 3,000 m인 삼각격자로 격자를 구축하였다. 혼합층을 분석하기 위하여 수직격자 층은 50층으로 SZ(Sigma Z coordinate system)좌표계를 사용하였다. 초기·경계장은 FES(Finite Element Solution)2014, HYCOM(Hybrid Coordinate Ocean Model) 및 대기모델 결과를 이용하여 설정하였다. 수치모형 검증을 위하여 수온관측소에서 수심별 측정한 수온 값과 SCHISM 결과 값을 비교하였고, 상대오차가 약 10% 이내로 나타나 모형의 정확도를 확인하였다. 최종적으로 해수면 상승 및 해수온 상승 시나리오를 고려하여 계절별 연안해역의 혼합층 두께의 변화 양상에 대하여 검토하였다. 향후에는 보다 정밀한 대기모델과의 혼합모형 구축 및 다양한 수심 별 관측자료를 활용한다면 실무에서 적용 가능한 혼합층 분석 및 수산업 피해 발생 지역에 대한 피해저감 대책 수립이 가능할 것으로 판단된다.

• Journal of the Korean Geosynthetics Society
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• v.22 no.2
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• pp.13-21
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• 2023

Mean sea level has recently been rising due to global warming causing coastal erosion. As Korea is peninsula, the land loss due to coastal erosion is critical. An approach in this study is cementing the coastal area using bacteria, which is called microbially induced carbonate precipitation (MICP). This study tried to see how fresh water and sea water work with MICP as a solvent. Ureolytic activity during the MICP reaction was measured with deionized and sea water. A soil column was prepared to evaluate the strength of MICP-treated sand. Sands were treated by MICP with surface percolation method. As the treatmen t style was different with other conventional methods, several methods were proposed to properly evaluate the MICP-treated sand surface. A micro-scale evaluation was performed to assess the mineral structure treated by different solvents. As results, sea water rendered the ureolytic reaction slower. A needle penetrometer worked well to evaluate the MICP-treated sand surface. This study confirmed the utilization of sea water is feasible as the solvent of MICP.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.212-212
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• 2021

지구온난화에 따른 가장 큰 영향 중의 하나인 해수면 상승은 인구 및 산업시설이 집중되어 있는 연안에 심각한 영향을 미칠 수 있다. 연안 저지대 범람, 하천과 지하수로의 해수 유입, 하천의 수위증가, 조석 및 퇴적물의 변화 등의 직접적 피해를 증가시키고(국립해양조사원, 2012; Nicholls, 2002; 오상명 등, 2011), 시설물의 설계고 추산 및 흐름, 파랑의 흐름에 영향을 미쳐 연안 시설물의 안정성이나 기능성에 영향을 미치는 것으로 알려지고 있다(윤종주·김상익, 2012). 기후변화에 관한 정부간 협의체(Intergovernmental Panel on Climate Change, IPCC)의 5차 보고서(2014)에 따르면, 1901~2010년 동안 전 지구 평균해수면 상승률은 1.7mm/year에 이르며, 1990년대 이후에 더 높은 해수면 상승률을 예측하였다. 우리나라의 경우, 2010년 말까지의 자료분석 결과에서 2.48mm/year의 연평균 해수면 상승률을 보여 전세계 평균상승률보다 훨씬 상회하는 것으로 보고되고 있다(정태성, 2014; 윤종주 등, 2012). 이와 같이 전 지구적 평균해수면의 변화와는 별개로 지역적 해수면 변동특성은 그 양상이 크게 다를 수 있으며, 이는 지구온난화와 같은 자연적인 요인 뿐만 아니라 지역별 다양한 인위적 요인(풍속, 기압, 연안역 개발정도 등)에 따라 지역적 해수면 상승이 크게 변화할 수 있다. 이에 본 연구에서는 국내 연안역에 분포한 조위관측소의 장기 관측자료(수위)를 이용하여 각 지역별 해수면의 상승경향을 분석하였으며, 동/서/남해안 및 제주권역은 권역별 조석특성이 현저하게 다른 특성을 보이므로 권열별로 구분하여 분석이 수행되었는데 우리나라 대부분의 관측지점에서 평균해수면이 증가하는 추세인 것으로 나타났다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.4
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• pp.305-315
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• 1983

A survey was carried out from July to December in 1979 and 1982 for the investigation of oceanographic conditions and phytoplankton in Seogwipo coastal area. Although a peculiar coastal sea water is formed by in flowing of fresh water, this is developed mainly in summer and disappeared or weakened in its strength after November. However, this coastal sea water covers only the surface while in mid and bottom layer open sea water is approached to the coast. Therefore, coastal and open sea water appears simultaneously in narrow sea area. Mean values of nutrient concentrates on surface layer during investigating period were $3.72{\sim}16.34{\mu}g-at/l$ in silicate, $1.98{\sim}5.53{\mu}g-at/l$ in nitrate and $0.34{\sim}0.90{\mu}g-at/l$ in phosphate. These showed slight differences among places but in general coastal side were lower than open sea side. Phosphates which is the lowest in concentrates among nutrients in Seogwipo coastal area shows almost similar value with Jinhae Bay but higher than open sea water around 10 mile south of Seogwipo. In general, seasonal changes of nutrients in investigating period shows a tendency of the lowest in October, increasing in November, and again slight decrease in December. As a phytoplankton fauna, 48 species, 1 variety and 2 breeds of Diatoms, 29 species, 3 varieties and 1 breed fo Dinoflagellates, and 1 species each of Chroococcus and Trichoceratium were found. Monthly predominant species are all neritic: Rhizosolenia sp. and Ceratium sp. in August, Chaetoceros sp., Ceratium sp. and Peridinium sp. in September, Astrionella sp. and Peridinium sp. in October, Astrionella sp., Navicula sp. and Chaetoceros sp. in November Among these, Rhizosolenia alata f. gracillima in August and Astrionella gracillima in November are remarkable predominant.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.4
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• pp.457-467
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• 2019

To investigate the long-term variation characteristics of nutrients in the east coast of Korea, water temperature, salinity, dissolved oxygen, and nutrients were measured at three stations of Sokcho, Jukbyeon and Gampo coasts for five years from 2013 to 2017. For five years, the water temperature of the East Sea coast was in the range of $1.2{\sim}28.8^{\circ}C$, the salinity was in the range of 30.63~34.79 and the dissolved oxygen (DO) was in the range of 3.53~7.64 mL/L. Distribution and variation of the water environment factors in the study area were determined by the vertical stratification of water column and distribution of water temperature. The high DO concentration in Sokcho coast From 2015 to August 2016 is presumed to be the result of the southward inflow of North Korean Cold Water (NKCW). Concentrations of dissolved inorganic nitrogen (DIN, $NH_4-N+NO_2-N+NO_3-N$) ranged $0.11{\sim}24.19{\mu}M$, phosphate concentration ranged $0.01{\sim}1.75{\mu}M$, and silicate ranged $0.17{\sim}32.80{\mu}M$. The N:P ratio was in the range of 0.7~54.3 (mean 15.2) and the N:P slope was in the range of 11.67~13.75. The N:P ratios in this study were lower than the Redfield ratio (16), indicating that nitrate did act as a limiting factor in phytoplankton growth. The correlation ($R^2$) of total N:P ratio was as high as 0.95, indicating that the effect of the surrounding land or non-point sources was not significant. In conclusion, the spatial and temporal variation of nutrients in the east coast of Korea was determined by the vertical mixing of water mass with thermocline and mainly affected by physical factors such as influx of external water masses and coastal upwelling, and the influences from inflows from the land were minimal.