• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.927-929
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• 2005

In this paper, through the theoretical study on reducing method and analysis of stray load loss of induction motor, we suggest the improved design considering the slot combination, skew, air gap and manufacturing method. For verifying the suggested design, the test was performed by IEEE 112. As a result, the reducing technology on the stray load loss was established.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2019.05a
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• pp.82-82
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• 2019

해상에서 긴급상황 발생 시 선박운항자는 짧은 시간에 신속 정확한 의사 결정을 할 필요가 있다. 이를 위해서 해양사고(충돌, 좌초, 화재, 엔진고장, 조타고장) 심각성에 따른 대피항로(해경선, 비상투묘, 표류, 임의좌주, 주변선박) 선정 알고리즘을 설계하였고, 선박운항자를 위한 긴급대피지원안내 시스템을 개발 중에 있다. 본 연구에서는 대피항로 선정 지원 기술 중 비상투묘와 충돌위험도를 중심으로 시스템 적용 모델의 타당성의 평가하고 알고리즘의 신뢰성을 검증하였다. 비상투묘 지원 기술의 검증을 위해 국내외 해양사고 보고서 및 재결서를 분석하고 알고리즘에 적용해 결과를 비교하였다. 충돌위험도를 검증하기 위해 재결서의 선박 충돌 사고 사례를 시뮬레이션으로 재현하였고, 시뮬레이션 기록 데이터를 기반으로 PARK model, IWRAP MK2 프로그램을 이용해 충돌위험도를 평가하였다. 본 연구의 결과를 통해 해양사고 발생 시 선박과 인명 피해를 최소화할 수 있을 것으로 예상된다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.11a
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• pp.77-79
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• 2023

국내 대표 해양도시인 부산시는 도시의 이미지를 향상시키고 경쟁력을 갖추기 위해 북항재개발지역과 원도심지역을 연계한 복합형 재생사업을 추진하고 있다. 부산남항은 북항과 원도심지역에 맞닿아있지만 고유의 특성이 고려되지 못하고 복합형 재생사업에 종속된 개발 압력을 받아왔다. 최근 해양관광벨트 형성에 있어 부산남항의 입지적 중요성과 북항·원도심지역과의 연계 필요성이 대두되며 부산남항을 대상으로 다양한 개발계획이 수립되고 있다. 항만재개발사업의 경우 대규모 SOC사업으로 추진과정에서 이해관계자 간의 갈등, 재정 문제 등의 여러 문제가 야기되는데 이러한 문제를 해결하지 못하면 사업이 표류 될 가능성이 크다. 따라서 본 연구는 부산남항 재창조를 위해 필수적인 항만재개발사업의 원활한 진행을 위한 추진전략과 민간참여방안을 제시하였다.

• Journal of Soil and Groundwater Environment
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• v.10 no.3
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• pp.38-45
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• 2005

The feasibility of stimulating in situ aerobic cometabolic activity of indigenous microorganisms was investigated in a trichloroethylene (TCE)-contaminated aquifer. A series of single-well natural drift tests (SWNDTs) was conducted by injecting site groundwater amended with a bromide tracer and combinations of toluene, oxygen, nitrate, ethylene and TCE into an existing monitoring well and by sampling the same well over time. Three field tests, Push-pull Transport Test, Drift Biostimulation Test, and Drift Surrogate Activity Test, were performed in sequence. Initial rate of toluene degradation was much faster than the rate of bromide dilution resulting from natural groundwater drift, indicating stimulation of indigenous toluene-oxidizing microorganisms. Transformation of ethylene, a surrogate probing overall activity of TCE transformation, was also observed, and its transformation results in the production of ethylene oxide, suggesting that some tolueneoxidizing microorganisms stimulated may express a orthomonooxygenase enzyme. Also in situ transformation of TCE was confirmed by greater retardation of TCE than bromide after the stimulation of toluene-oxidizing microorganisms. These results indicate that, in this environment, toluene and oxygen additions stimulated the growth and aerobic cometabolic activity of indigenous microorganisms expressing orthomonooxygenase enzymes. The simple, low-cost field test method presented in this study provides an effective method for conducting rapid field assessments and pilot testing of aerobic cometabolism, which has previously hindered application of this technology to groundwater remediation.

• Korean Journal of Environmental Biology
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• v.18 no.1
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• pp.153-161
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• 2000

This study was carried out to examine the drift of Gammarus sobaegensis by acid stress as pH depression in Oweol creek from April 1996 to October 1996. The behavioral drifting was revealed to the characteristics of G. sobaegensis that is tend to increase as acid stress. And, tolerance level of G. sobaegensis to pH depression was different among the size classes. Individuals belong to small to medium size classes were weak in lower pH. Pattern of response in G. sobaegensis has a lower tolerance to acid stress at below pH 4.0 than above pH 5.0 in the artificial channel and show the possibility as an effective aquatic ecotoxicity test organism. The result of analysis of variance, water temperature (F-ratio : 66.596, p< 0.0005) and the size classes (F-ratio : 71.386, p< 0.0005) except pH level (F-ratio : 353.415, p<0.0005) were showed to the major factor for drift behavior by acid depression. [Gammarus, pH, Drift, Acid stress, Ecotoxicity test].

• 한국해양학회지
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• v.30 no.5
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• pp.467-479
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• 1995

To investigate the current structures and diffusion characteristics in Youngil Bay, a systematic field observations of current velocity, drogue tracking, dye diffusion experiment and aerial photographing were performed. The flow patterns in the surface layer of the bay depend more strongly on the wind and ocean current than the tidal current, and the patterns in the middle are predominated by the ocean current. The residual currents in the surface generally flow toward the inner bay through the western and central areas of the bay, and then the currents go toward the ocean along the eastern shore of the bay with anti-clock-wise circulation. The residual currents in the surface of the eastern cease are not nearly influenced by the wind, and the currents always move northward to northeastward. However, the currents in the western shore depend strongly on the wind and the outflow of the Huntsman River, that is, the residual currents go northward to northeastward when the southerly to westerly winds blow or a large amount of flow from the river discharge. The residual currents in the middle layer flow toward the inner bay along the western shore of the bay, and the incomed currents go out to the ocean along the eastern shore with anticlockwise circulation. The diffusion of dye patch by the instantaneous point source shows a similar pattern to the drogue trajectory, and the apparent diffusion coefficients of the dye patch by Fick's theory is 1.14${\times}$10$^4$ cm$^2$/s. The behavior of the river discharges in flood shows a band type's effluent pattern toward the outer bay along the western coast.

• Tunnel and Underground Space
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• v.25 no.2
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• pp.125-132
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• 2015

As for noise and vibration occurring due to construction near fish farms, engineering and the technical opinions of experts in different areas were excluded in calculating any damage. The victims tend to present only biological consulting-based opinions while construction companies tend to present information on general construction noise and vibration as they have little biological knowledge on fish. So, the National Environmental Dispute Medication Commission presented specific damage standard in 2009 through studies on standard in calculating compensation and damage assessment of farm-raised fish that were affected by noise and vibration. Currently, 140 dB re $1{\mu}Pa$ is accepted as damage standard of underwater noise in the country. This standard is the RMS value of continuous sounds for more than a second, not the impulsive sounds. To look up the data on existing studies, fish showed different reactions to underwater sounds according to the different kinds of fish such as ostariophysan or non-ostariophysan, and pinnipeds or non-pinnipeds. So, this study will present damage standards for impulsive sounds in consideration of the differences in the characteristics of the impulsive and continuous sounds.

• Korean Journal of Remote Sensing
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• v.16 no.3
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• pp.211-220
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• 2000

Even though recurring eddies at the terminal end of the East Korean Warm Current have been identified in the thermal infrared imagery from the NOAA/AVHRR sensor and ocean color data from Orbview-2/SeaWiFS sensor, it is difficult to make observation in the field regarding recurring eddies located around the Wonsan coastal area in North Korea. But we could get in situ data related to an eddy from an ARGOS satellite tracking drifter trapped in the eddy on January 4th, 1999. An ARGOS drifter, a NOAA satellite tracked buoy was trapped by the eddy during January 4th.March 18, 1999. The ARGOS drifter rotated 10 times per 72 days on the edge of the eddy located at $39^{\circ}N$, $129^{\circ}E$. The diameter of the eddy was about 100 km. The horizontal rotation velocity of the recurring cold-core anti-cyclonic eddy was 1.53 km/h(42 cm/sec). The sea surface temperatures of the eddy varied from $14.7^{\circ}C$ on January 5, 1999 to $9.6^{\circ}C$ on March 18,1999. To study the mechanism of the recurring eddy. we tried to find out the relationship between the vector of the drifter moving in the eddy and the wind vector in Sokcho and Ulleung Island located near the eddy in southern Korea, and the difference in sea level between Ulleung Island and Mukho. We hope the results of this study would be useful for calibration and validation data of simulation and numerical modeling studies of the recurring eddy.

• Journal of Navigation and Port Research
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• v.44 no.6
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• pp.439-446
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• 2020

The IMO has adopted emission standards through Annex VI of the International Convention for the Prevention of Pollution from Ships (MARPOL) that strictly prohibit the use of bunker C oil for vessels. In this study, we have adopted the turret-moored Floating LNG-Bunkering Terminal (FLBT) which is designed to receive the LNG from LNGCs and transfer it to LNG-bunkering shuttles in side-by-side moored condition. Numerical analyses were carried out using the high-order boundary-element method for four vessels at various relative distances. Mean wave drift forces were compared in an operational sea state. A model test was performed in the ocean engineering basin at the Korea Research Institute of Ships & Ocean Engineering (KRISO) to verify the safety of the berthing/unberthing operation. In the model test, a jig was designed to simulate tug boats pushing or pulling the bunkering vessels, so that the friction force of the g operation was not affected. Safety depended on the environmental direction, with more stable operation possible if the heading-control function of FLBT is applied to avoid beam-sea conditions.

• Bulletin of the Society of Naval Architects of Korea
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• v.20 no.4
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• pp.33-40
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• 1983

The drift force acting on a freely-floating sphere in water of finite depth is studied within the framework of a linear potential theory. A velocity potential describing fluid motion is determined by distribution pulsating sources and dipoles on the immersed surface of the sphere. Upon knowing values of the potential, hydrodynamic forces are evaluated by integrating pressures over the immersed surface of the sphere. The motion response of the sphere in water of finite depth is obtained by solving the equation of motion. From these results, the drift force on the sphere is evaluated by the momentum theorem, in which a far-field velocity potential is utilized in forms of Kochin function. The drift force coefficient Cdr of a fixed sphere increases monotononically with non-dimensional wave frequency ${\sigma}a$. On the other hand, in freely-floating case, the Cdr has a peak value at ${\sigma}a$ of heave resonance. The magnitude of the drift force coefficient Cdr in the case of finite depth is different form that for deep water, but the general tendency seems to be similar in both cases. It is to note that Cdr is greater than 1.0 when non-dimensional water depth d/a is 1.5 in the case of freely-floating sphere.