• 한국산업융합학회 논문집
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• 제10권1호
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• pp.15-20
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• 2007

The aim of this study is to measure the removal characteristics of organic matter and bacteria with the use of ozone to reduce the problems caused by bacteria and organic matter which appear in sea-water is summer season. When the total input of ozone was $1.4mg/{\ell}O_3$, the removal rate of bacteria and E-coli from sea-water proved to be 100%. With the same input of ozone, on the other hand, the removal rate of COD turned to be relatively low, 50%, which was to the fact that sea-water consists of salt matter which is a kind of COD matter. This result supports the idea that we can keep using ozone steadily in the future to remove organic matters and bacteria from sea-water because ozone destructs relatively less salt matter in sea-water. Also, the treatment effect rate of SS, turbidity and organic matters such as $NH_3$-N, $NO_3$-N etc, was very high. As a result, we assume that the treatment of organic matter in sea-water with ozone is very effective

• 한국해양공학회지
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• 제13권2호통권32호
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• pp.116-128
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• 1999

A deep water wave prediction model applicable to the East Sea is presnted. This model incorporates rediative transter of energy specrum, atmospheric input form the wind, nonlinear interaction, and energy dissipation by white capping. The propagation scheme by Gadd shows satisfactory results and the characteristics of the nonlinear interaction is simulated well by discrete interaction approximatiion. The application of the model to the sea around the Korean Peninsula shows reasonable agreement with the observation.

• 한국해양공학회지
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• 제10권3호
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• pp.14-23
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• 1996

The corrosion fatigue test were carried out to evaluate the fatigue characteristics of accelerated cooled (ACC) TMCP high tensile strength steels and weld joint with high heat input by one side one run submerged are welding. In this paper, the fatigue crack growth behaviors were investigated with the center crack tension specimen of base metal and heat affected zone in substitute sea water and air, respectively Main results obtained are sunnarized as follows: 1. The fatigue crack growth rates in sea water faster than those in air environment for the different heat input values, crack growth rate of base metal is very fast and effect of heat input is not remarkable. 2. In HAZ (82kJ/cm, 116kJ/cm), the crack branching phenomena were observed in both air and sea water environment, 3. In SEM observation, the corrosion effect on base metal was larger than that on HAZ in corrosion environment.

• 수산해양기술연구
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• 제30권1호
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• pp.25-32
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• 1994

An underwater speaker was made of a moving coil driver unite of usual speaker, acryl-boards, polyester resin, rubber and castor oil and it's frequency characteristics was measured in range of 250~600Hz in air water tank and sea. The results of measurements are follows: 1. Transmitting and receiving frequency of measurement frequency were similar in air, water tank and sea. 2. The input and output wave forms of a manufactured speaker which is not water-proof in air were similar to each other in 300~450Hz, but other frequencies showed distorted wave forms. 3. The input and output wave forms of an underwater speaker in water thank and sea were similar to each other in 250~600Hz. But output wave forms showed combination waves with very low frequency. 4. Transmitting and receiving frequency wave forms and resisting pressure of an underwater speaker at 80m in the depth of water were in good condition. Therefore it can be possible to use it as an underwater speaker.

• Ocean and Polar Research
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• 제33권3호
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• pp.291-301
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• 2011

To investigate major factors controlling variations in water quality, principal component analysis and cluster analysis were used to analyze data sets of 12 parameters measured at 23 sampling stations of Jinhae Bay during winter and spring. Principal component analysis extracted three major factors controlling variations of water quality during winter and spring. In winter, major factors included freshwater input, polluted material input, and biological activity. Whereas in spring they were polluted material input, freshwater input, and suspended material input. The most distinct difference in the controlling factors between winter and spring was that the freshwater input was more important than the polluted material input in winter, but the polluted material input was more important than the freshwater input in spring. Cluster analysis grouped 23 sampling stations into four clusters in winter and five clusters in spring respectively. In winter, the four clusters were A (station 5), B (stations 1, 2), C (station 4), and D (the remaining stations). In spring, the five clusters included A (station 5), B (station 1), C (station 3), D (station 6), and E (the remaining stations). Intensive management of the water quality of Masan and Hangam bays could improve the water quality of Jinhae Bay since the polluted materials were mainly introduced into Jinhae Bay through Masan and Hangam bays.

• 한국해양학회지
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• 제24권3호
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• pp.121-131
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• 1989

1982년과 1983년 여름 한국 남동 해안부근에서 관측된 냉수를 수온, 염분, 해면, 바람 및 인공위성 영상의 자료를 이용하여 연구하였다. 3층구조의 해양을 보이는 여름철에 수일 동안 지속되는 단속적인 남서풍에 의해 완벽한(full) 용승현상이 나타난다. 용승기간 동안에 고온의 표층수는 외해로 이동하였고, 저온의 중층수가 해표면으로 노출하였으며, 해면은 하강되었으나 표층의 균형(equilibrium) 깊이는 변화되지 않았었다. 관측결과는 해표면의 냉수가 중층으로부터 기원되고 강한 전선은 계절 수온약층이 해표면에 상승된 결과임을 보인다. 해표면 전선위치와 바람입력사이의 상관관계 파악을 위해 Csanady(1982)의 모델을 rigid lid 근사조건에서 해를 구하였다. 그 결과는 전선의 위치가 바람입력 및 한국 남동 해안부근의 해양구조에 의해 결정될 수 있음을 보이고 있다. 여름철 냉수는 $10m^2/sec$ 크기 정도인 최소 바람역적보다 큰 바람이 작용될 경우에만 해표면에 나타날 수 있다.

• 환경영향평가
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• 제21권3호
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• pp.445-460
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• 2012

In order to evaluate and predict the environmental impact of the low-trophic-level ecosystem to environmental changes in the Yellow Sea and the East China Sea, an ecological modelling study was undertaken. Simulation results of average distribution patterns and concentrations of water quality factors during the summer by the model were acceptable. Phytoplankton and remineralization rate of organic matter were very important parameters by a sensitivity analysis. Water quality factors showed high values in the estuary of the Yangtze River and in the West and South Sea of Korea and low values in the central area of the Yellow Sea. There is a plume of high values, especially nutrients, off the mouth of the Yangtze that expands or contracts with changes in the discharge strength. Characteristics of responses of water quality factors vary for different scenarios of environmental change, such as land-based pollution sources and atmospheric forcing. It is suggested that changes of light intensity, discharges of input sources, and wind play an important role in the marine ecosystem.

• 환경생물
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• 제33권2호
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• pp.223-229
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• 2015

Pre-monsoon dynamics of zooplankton community were investigated in the downstream of the Gagok stream flowing into the East Sea of Korea. Monthly sampling was carried out to collect zooplankters at five sites in the stream during the period between April and July 2014. Dissolved oxygen contents exceeded $7.0mg\;L^{-1}$ all the time. Water temperature was in a range of 15.7 to $24.9^{\circ}C$ and pH 7.4 to 8.8, respectively. A total of 75 taxa consisted of 36 species of rotifers, 16 species of cladocerans, 16 species of copepods, four kinds of aquatic insects, two kinds of decapods and one nematod was occurred. One species of marine copepod and one cladoceran, and one species of brackish rotifer and one copepod distributed at the station located in the stream mouth. Zooplankton abundance showed to vary from 42 to 4202 individuals $m^{-3}$ due to the explosion of aquatic insects and Alona sp. at site 2 located in the downstream in April. Heavy rainfall during the monsoon period seems to decrease the zooplankton abundance caused by diffusion and drifting to the sea. Species diversity indices were generally high between 1.2~2.3 and were recorded to be high at the downstream throughout the study period. With the zooplankton dynamics, the influence of the input of sea waters into the stream seemed to be confined to some hundred meters of the stream mouth facing the East Sea.

• 한국해양공학회지
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• 제19권1호
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• pp.14-19
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• 2005

As a basic study for establishing the input conditions of a forecasting/estimating model, used for deep-sea water drainage to the ocean, this study was carried out as follows: 1) estimating the amount of river discharge and pollutant loads into the developing region of deep sea water in the East Sea, Korea, 2) a field observation of tidal current, vertical water temperature, and salinity distribution, 3) 3-D numerical experiment of tidal current to analyze the physical oceanographic status. The amount of river discharge flowing into this study area was estimated at about $462.7{\times}103 m\^3/day$ of daily mean in 2002. Annual mean pollutant load of COD, TN, and TP were estimated at 7.02 ton-COD/day, 4.06 ton-TN/day, and 0.39 ton/day, respectively. Field observation of tidal current normally shows 20-40cm/sec of current velocity at the surface layer, and it decreases under 20cm/sec as the water depth increases. We also found a stratification condition at around 30m water depth in the observation area. The differences in water temperature and salinity, between the surface layer and the bottom layer, were about 18 C and 0.8 psu, respectively. On the other hand, we found a definite trend of 34 psu salinity water mass in the deep sea region.

• 한국해양공학회지
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• 제33권2호
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• pp.178-188
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• 2019

When burying underwater cables using robots, heading control is one of the key functions for the robots to improve task efficiency. This paper addresses the heading control issue for URI-T, an ROV for underwater construction tasks, including the burial and maintenance of cables or small diameter pipelines. Through modeling and identifying the heading motion of URI-T, the dynamic characteristics and input limitation are analyzed. Based on the identification results, a PD type controller with appropriate input treatment is designed for the heading control of URI-T. The performance of the heading controller was verified in water tank experiments. The field applicability of the proposed controller was also evaluated through the sea trial of URI-T at the East Sea, with a water depth of 500 m.