• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2006년도 추계학술발표회
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• pp.163-168
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• 2006

동해의 해양 심층수 자원 기반 환경 연구의 일부로 청결기술을 적용하여 해수 중의 용존성 미량금속 (Cd, Co. Cu, Ni. Ph. Zn) 농도 분포와 변화를 조사하였다. 강원과 경북 지역에 총 6개 정점을 선정하고, 각 지역마다 최대 채수 수심 각각 200-300m 와 500m 까지 시료를 채취하였다. 본 연구의 미량금속을 위한 연안해수 표준물질 (CASS-4) 의 분석 결과 각 원소 평균 회수율은 Co의 89.4% 에서 Cd 의 99.8%의 범위였다. 용존 미량원소의 분포는 해역 및 시기적인 변화가 다양하게 나타났다 Cd, Ni, Zn의 경우는 영양염 의존형으로 표층에서 낮고 저층으로 갈수록 증가하는 경향이 뚜렷하였다. 그러나 Co, Cu, Ph 은 수직적으로 불규칙적인 분포를 나타내었다. 본 연구의 통해 심층수 원수의 중금속 농도는 해역별 수질 기준과 먹는 물 기준을 만족하였다.

• 한국환경과학회지
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• 제10권3호
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• pp.201-208
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• 2001

To investigate the physio-chemical components and properties of aerosol particles in urban area sampling of aerosol particles was carried out in the campus of Hokkaido University, Sapporo, Japan, during snowfall. Aerosol particles were collected on millipore filter papers using a low volume air sampler. Their shapes, sizes and chemical components were analyzed by a SEM(Scanning Electron Microscope) and an EDX(Energy Dispersive X-ray). As a results, ice crystals of dendrite and column types were predominantly shown at mature and developing stage of snowfall intensity. The denerite and sector plate types of ice crystals were mainly originated from the sea but column types were come from soil. Scavenging effect by snowfall was greatly also shown at dendrite type ice crystals that embryo was fully developd. Al, Si elements were shown at high frequencies as compared with others. Na, Cl components were especially shown at high frequencies under the sea-breeze wind during snowfall. Anthropogenic aerosol particles had shown with irregular shapes and sizes, relatively. Mainly 3-7$\mu$m aerosol particles were abundant and coarse particles also could be seen during snowfall. Ca, Zn, Fe components mainly caused by spike tires from vehicles in winter season were dominant before snowfall, however the element S mainly caused by human activity was rich after snowfall. The pH values of snow in Sapporo city were higher than those at coastal area. The concentration of chemical components in aerosol particles was also affected by surface winds. Aerosol particles in urban area, Sapporo were mainly affected by human activities like vehicles and combustion with wind system. And their types were related with snowfall intensity.

• 한국해양학회지
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• 제28권4호
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• pp.313-322
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• 1993

한국남서해역은 음향학적 특징에 따라 4개의 음향학적 퇴적상 (acoustic facies) 으로 구분된다. 고해상도 (3.5kHz) 물리탐사기록에 나타난 대표적인 음향학적 특징은 확산된 형(prolonged type), 내부 반사형(internal reflected type), 비투과 형 (non-penetrated type)과 투명한 형(transparent type)이다. 이러한 형(type)들은 해 저면 상황(bottom condition)과 퇴적물의 입도, 굳기(compaction)에 따라 변화한다. 음향학적 퇴적상 I은 확산된 형이 대표적으로 나타난다. 이 형은 불규칙 또는 규칙적 인 해저면 상황과 자갈, 패각편을 함유한 조립질퇴적물에 의해 음파신호가 하부로 흡 수되어 나타난다. 음향학적 퇴적상 II는 내부반사형이 나타난다. 내부반사구조는 퇴적 물의 굳기변화에 의해 발생하는 것으로 추측된다. 음향학적 퇴적상 III은 비투과 형이 나타난다. 이는 분급이 양호한 세립사와 극세립사가 퇴적된 곳에서 음파신호가 투과 하지 못하고 해저면에서 산란되어 나타난다. 음향학적 퇴적상 IV는 일정한 층후에 내 부반사 구조가 없는 투명한 형이 나타난다. 고해상도 물리탐사 기록상에 나타난 음향 학적 형들은 퇴적층서 뿐만 아니라 천해저의 퇴적기작에 대한 중요한 정보를 나타낸 다.

• 해양환경안전학회지
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• 제3권1호
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• pp.33-49
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• 1997

One of the most important missons that are imposed on merchant ship at sea is to accomplish the safe transportation of cargo loaded. Recently, a study on the seakeeping performance has been carried out on the development of evaluation system related to the synthetic safety of a ship at sea. The seakeeping performance is the ship's ability sailing at, and executing its misson against adverse environmental factors successfully and safely. Until now, however, there has not been any method of quantitative evaluation on the dynamic safety of the ship's cargo loaded. In this regards, this paper has introduced the evaluation method of dynamic safety of the ship's cargo. In order to evaluate the dynamic safety of cargo, the vertical and lateral acceleration which causes the collapse, racking and local structure failure of cargo was adopted as the evaluation factors in the ship's motions. The response amplitude of ship's motions in regular waves is manipulated by NSM (New Strip Method) on a given 2,700 TEU full container vessel under the wind forces of 7, 8 and 9 Beaufort scale. Each response of ship's motions induced by NSM was applied to short-crested irregular waves for stochastic process on evaluation factors and then vertical and lateral acceleration of each cargo was compared with significant amplitude of each acceleration. A representative dangerous factor was determined by comparing permissible values of stacking and racking forces occurred typically to the vertical and transverse directions with the container strength required on ISO 1496 at the positions of forecastle, poop and ship's midship respectively. Through the occurrence probability of the determined factor by Rayleigh's probability density function, the dangerousness which limits loads on container's side wall as an evaluation was applied in judging of the danger of the ship's cargo loaded.

• The Journal of the Acoustical Society of Korea
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• 제26권2E호
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• pp.44-49
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• 2007

Donghae City - Ulleung Island Line (DC-UI Line) is a representative line for underwater and geoacoustic modeling in the middle western East Sea. In this line, an integrated model of P-wave velocity is proposed for a low-frequency range target (<200 Hz), based on high-resolution seismic profiles (2 - 7 kHz sonar and air-gun), shallow and deep cores (grab, piston, and Portable Remote Operated Drilling), and outcrop geology (Tertiary rocks and the basement on land). The basement comprises 3 geoacoustic layers of P-wave velocity ranging from 3750 to 5550 m/s. The overlying sediments consist of 7 layers of P-wave velocities ranging from 1500 to 1900 m/s. The bottom model shows that the structure is very irregular and the velocity is also variable with both vertical and lateral extension. In this area, seabed and underwater acousticians should consider that low-frequency acoustic modeling is very range-dependent and a detailed geoacoustic model is necessary for better modeling of acoustic propagation such as long-range surveillance of submarines and monitoring of currents.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.167-171
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• 2004

The Spar platform with deep draft is characterized as effective structure in extreme wave condition, which has larger natural period than that of waves in sea. In this paper, the time simulation of motion responses of Spar with catenary mooring line is presented in irregular waves. The memory effect is modeled by added mass at infinite frequency and convolution integrals in terms of wave damping coefficients. The added mass, wave damping coefficients and wave exciting forces are obtained from three-dimensional panel method in the frequency domain. The motion equations are consisted of forces for inetia, memory effect, hydrostatic restoring, wave exciting and mooring line. The forces of mooring line are modeled as quasi-static catenary cable.

• International Journal of Naval Architecture and Ocean Engineering
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• 제2권1호
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• pp.14-23
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• 2010

A numerical model was developed for simulating a three-dimensional multilayer hydrodynamic and thermodynamic model in domains with irregular bottom topography. The model was designed for examining the interactions between flow and topography. The model was based on the three-dimensional Navier-Stokes equations and was solved using the fractional step method, which combines the finite difference method in the horizontal plane and the finite element method in the vertical plane. The numerical techniques were described and the model test and application were presented. For the model application to the northern part of Ariake Sea, the hydrodynamic and thermodynamic results were predicted. The numerically predicted amplitudes and phase angles were well consistent with the field observations.

• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.520-526
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• 2006

Wave Energy is a derivative of the solar energy input to the earth, which is accumulated on open water surfaces by the action of the winds Waves are disturbances in the water surface. This paper is interested primarily in progressive waves, which carry energy from one place to another Waves are irregular in size and frequency. Moreover the surface of the sea is one of the most hostile environments for engineering structures and materials. The idea of harnessing the tremendous power of the ocean's waves is not new. Hundreds of wave energy conversion techniques have been suggested over the last two centuries. Although many WECS (Wave Energy Conversion Systems) have been invented, only a few systems have been tested and evaluated. This paper describes the characteristic of WES (Wave Energy System) in terms of, devices, resource and potential, etc.. Finally, this paper provides a summary of general and specific conclusions and recommendations concerning WECS potential in Korea.

• 한국항해학회지
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• 제11권1호
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• pp.67-91
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• 1987

In this paper, a synthetic method for evaluating the seakeeping performance of a ship in waves is studied. For the prediction and evaluation of irregular phenomena to be correlated each other, the multi-dimensional Rayleigh's joint probability density function and the cumulative distribution function are approximated. According to this approximated function, it is able to calculate easily the occurrence probability of the factors on seakeeping performance. We proposed an evaluation method and an index to be defined by the seakeeping performance reliability, that is considered as the dangerousness and the relative dangerousness of the factors on seakeeping performance in waves. The use of this method aid index will be effective to install the sensors which are necessary to evaluate the states of ships at sea. Some example of the calculations by this method for 175m length single screw container ship equipped with diesel engine are also presented.

• 한국해안해양공학회지
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• 제7권4호
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• pp.321-328
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• 1995

PCGS(preconditioned conjugate squared) 방법을 사용한 음해법적 조석모형인 FIT(fully implicit tidal)모형을 개발하여 목포항 인근해역에 적용하였다. M$_2$분조에 따른 유속과 조위에 대한 검증결과 만족할 만한 결과를 얻었으며, 빠른 유속을 갖는 협수부와 수심과 지형이 복잡한 곳에서도 모형의 타당성이 입증되었다. 개발된 모형을 통해 목포구의 완충효과를 규명하여 하구언 및 방조제 건설에 따른 목포항 부근의 조석 확폭현상을 파악할 수 있었다.