• 한국항만학회지
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• 제12권2호
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• pp.323-328
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• 1998

A quartz crystal analyzer is utilized to monitor the corrosion process of an aluminum surface of a quartz crystal for marine sensor by sea water. A quartz crystal having 2000 $\AA$ of aluminum layer is installed in a specially designed cell and is in contact with sea water imitated electrolyte solution. While a constant potential is applied to the cell, the resonant frequency and resonant resistance are simultaneously measured using the quartz crystal analyzer. In addition, surface topographs are taken with an atomic force microscope(AFM) and the element analysis of the surface is conducted using an energy dispersive X-ray spectrometer(EDX). The simultaneous measurement of resonant frequency and resonant resistance during the corrosion process explains the change of surface structure caused by the corrosion. The variation of resonant frequency addresses the amount surface metal dissolution. As a conclusion, it is found that a simple measurement using the quartz crystal analyzer can replace the complex monitoring employing large equipments in the investigation of a corrosion process of sensor surface.

• 한국환경과학회지
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• 제4권2호
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• pp.121-139
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• 1995

Based on the Results of Marine Meteorological and Oceanographical Observations (1966 -1987), the phenomenon of chimney is found as a candidate for the formation of the Japan Sea Proper Water (JSPW). The chimney phenomenon occurs twelve times Inuring 1966∼ 1987. The water types in the chimney denoting the deep convection are similar to those of the JSPW 0∼ 1℃ in potential temperature, 34.0∼34.1 ‰ in salinity and 68∼80 cl/t in potential thermosteric anomaly from the sea surface to the deep layer. The static stabilities in the chimney stations are unstable or neutral. This indicates that the winter time convection occurs. The JSPW sunken from the surface layer of chimney in winter spreads out under the Tsushima Warm Current area, following the isosteric surface of about 76 cl/t in Potential thermosteric anomaly. The formation of the deep water of the JSPW is mainly affected by the cooling of the sea surface than the evaporation of winds because the temperature and the salinity on the isoteric surface of about 76 cl/t in potential thermosteric anomaly ate cold and low The phenomenon of chimney occurred in here and there of the area in the north of 40" 30'N, west of 138" E. This suggests that the deep water of the JSPW is formed not in a limited area but probably in the overall region of the northern open ocean.

• 한국환경과학회지
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• 제5권1호
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• pp.35-41
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• 1996

For studying of coagulation and sedimentation in estuarine clay, we obtained several flow curves with various concentrations of sea water by using Coutte type rotational rheometer. The initial shear stress on high concentration of sea water was observed big, but after this, its value is decreasing with increasing shear rate. The maximum pick of shear stress is decreasing with the decreasing of concentration of sea water The trend is same totally above for viscosity. The sedimentation times with the concentration of sea water vary in $\infty$ ~ 5 minutes. The zeta potential is changed dramatically between 114 and 118 concentration of sea water. That is consistent with the sedimentation graph. From these results, the phenomena of coagulation and sedimentation can be explained with viscoelastic terms on structual formation among particles by the changes of surface potential affected from contacting sea water to dispersed particles.

• 한국컴퓨터정보학회논문지
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• 제28권11호
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• pp.13-20
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• 2023

본 논문에서는 LSTM-Autoencoder 기반 특징추출과 재구성 데이터를 이용한 수온 예측 방법을 제안한다. 냉수대 현상이 발생한 동해 낙산 지역의 해수면 수온과 수온에 영향을 미치는 풍향, 풍속 등 다변량 시계열 데이터를 이용하고, LSTM-Autoencoder 모델을 이용하여, 원본 데이터의 차원 축소를 통해 추출된 특징 데이터를 원본 데이터의 다변수 데이터로 결합한 데이터, 복원 데이터, 원본 데이터 총 3가지를 사용한다. 수온 예측을 위해 LSTM 모델에 3가지 데이터를 학습하고, 정확도를 평가한 결과 MAE 0.3652, RMSE 0.5604, MAPE 3.309%으로 LSTM-Autoencoder의 특징추출을 이용한 수온 예측 정확도가 가장 우수한 성능을 보이는 것을 확인하였다. 본 연구의 결과는 냉수대와 같이 해수면 수온 변화가 급변하는 구간의 예측 정확도를 높여, 자연재해의 피해를 예방할 수 있을 것으로 기대한다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계 학술발표회 논문집(II)
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• pp.197-200
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• 2006

The ingress of chloride ions plays a crucial role for service life design of reinforced concrete structures. In view of durability design of concrete structures under marine environment, one of the most essential parameters is the surface chloride content of concrete. However, on the basis of the results of in-situ investigation, this value has been determining in the numerous studies on the durability design of concrete structures. Hence, it is necessary to confirm the range of the surface chloride content in order to establish a unified durability design system of concrete. This study suggests a rational and practical way to calculate the maximum surface chloride content of submerged concrete under marine environment. This approach starts with the calculation of the amount of chloride ingredients in normal sea water. The capillary pore structure is modeled by numerical simulation model HYMOSTRUC and it is assumed to be completely saturated by the salt ingredients of sea water. In order to validate this approach, the total chloride content of the mortar and concrete slim disc specimen was measured after the immersion into the artificial sea water solution. Additionally, the theoretical, the experimental and in-situ investigation results of other researchers are compiled and analyzed. Based on this approach, it will follow to calculate the maximum surface chloride content of concrete at tidal zone, where the environment can be considered as a condition of dry-wetting cycles.

• 한국표면공학회지
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• 제48권6호
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• pp.349-353
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• 2015

In this paper, arc thermal spray coating was conducted onto the SS400 steel using Inconel 625 wires in order to improve the durability of marine steel structures, and then investigated cavitation damage behavior of Inconel 625 coating layer in sea water. For the Inconel 625 coating layer, surface hardness appeared similar to that of existing high velocity oxy-fuel coating technology with 380~480 HV, but the porosity of about 6 % was larger relatively. During the cavitation experiment, pit damages were originated and grown at the rough surface and pore defect area of Inconel 625 coating layer. And, after the 72 hours of experimental time, weight loss of Inconel 625 coating layer exhibited gradually increasing tendency due to surface damage effect of the undercut.

• 한국지구과학회지
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• 제23권6호
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• pp.474-485
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• 2002

본 연구의 목적은 전라남도 완도군 고금도 지역 지하수의 수리지구화학과 수소-산소동위원소를 파악하여 해수침투경로와 오염여부를 규명하는데 있다. 연구지역 지하수의 물리적인 특성은 중성과 전이환경에 속하며, 해수와 지표수의 영향을 받은 것으로 나타났다. 화학적인 특성에서도 해수의 침투, 육상의 오 ${\cdot}$ 폐수 및 농약이나 폐기물에 의해 오염이 진행되고 있다. 특히 지하수 중 여섯 지역에서 Cl은 먹는 샘물 기준치를 초과하는 것으로 나타났다. 파이퍼도에서 GG-4와 14지역은 해수의 침투로 오염되었으며, 수질유형을 구분하여 보면 GG-3, 7 및 13지역은 Na와 HCO$_{3}$가 지배적이고, GG-14지역은 해수와 같이 Na와 Cl이 지배적으로 나타났다. 수리지구화학적인 모델링 분석결과 해수의 방해석과 백운석 포화지수는 과포화상태이며, GG-3, 14 및 18지역에서 포화영역에 접근하고 있다. 수소-산소동위원소비에서 본 역 지하수의 기원은 순환수이며, GG-1, 5 및 14지역의 높은 산소동위원소는 지표수의 유입과 해수 침투에 의한 것이다. 본 연구결과 GG-14지역의 지하수는 해수의 침투에 의해 오염되어 있으며, GG-3, 7 및 13지역을 제외한 지하수들은 해수의 침투 및 인위적인 오염원에 의해 오염이 진행되고 있다.

• 한국해양공학회지
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• 제26권1호
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• pp.78-83
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• 2012

The abundant nutrients contained in deep seawater are delivered by natural upwellings from the deep sea to the surface sea. However, the natural upwelling phenomenon is limited to specific areas of the sea; in other areas, the thermocline separates the surface sea from the lower layer. Thus, the surface layer is often deficient in nutritive salts, causing the deterioration of its primary productivity and ultimately leading to an imbalance in the marine ecosystem. Without a consistent supply of nitrogenous nutritive salts, they are absorbed by phytoplankton, resulting in a considerable problem in primary productivity. To solve this issue, a floating type of artificial upwelling system is suggested to artificially pump up, distribute, and diffuse deep seawater containing rich nutritive salts. The key technologies for developing such a floating artificial upwelling system are a floating offshore structure with a large diameter riser, self-supplying energy system, density current generating system, method for estimating the emission and absorption of CO2, and way to evaluate the primary production variation. Strengthening the primary production of the sea by supplying deep seawater to the sea surface will result in a sea environment with abundant fishery resources.

• 한국수산과학회지
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• 제41권6호
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• pp.505-510
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• 2008

To understand the oceanographic characteristics of Hupo coastal waters as regards the East Korean Warm Current and the North Korean Cold Current, current direction and velocity were investigated by deploying a current meter in Hupo coastal waters during the summer and fall of 2007. Wind data were obtained from the homepage of the Korea Meteorological Administration. Water temperature was measured using a temperature meter attached to the current meter and a mini log. During summer, a south wind prevailed, while during the fall the wind blew from the north. Cold surface waters occurred on a large scale in summer, while in the fall, warm bottom water occurred frequently. After mid-November, when the surface water was cooler than $15^{\circ}C$, there was no difference in water temperature between the surface and bottom layers.

• 한국수산과학회지
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• 제40권2호
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• pp.102-107
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• 2007

A remarkable sea surface cooling (SSC) event was observed in the eastern sea of Korean peninsula based on new generation sea surface temperature (NGSST) satellite images in September 2005, when typhoon Nabi passed over the East Sea. The degree of SSC ranged from $1^{\circ}C\;to\;4^{\circ}C$, and its maximum was observed in the southeastern sea area. Daily variations in sea surface temperature at a longitudinal line $(35^{\circ}-41^{\circ}N,\;132^{\circ}E)$, derived from satellite data for September 1-13, 2005, showed that the SSC lasted about 3 days after the typhoon passed in the south of $39^{\circ}N$, whereas it was unclear in the north of$39^{\circ}N$. Water temperature measured by a mooring buoy suggested that the SSC was caused mainly by a vertical mixing of the water column driven by the typhoon, rather than by coastal upwelling.