• 대한조선학회논문집
• /
• 제51권3호
• /
• pp.254-258
• /
• 2014

Field trial in ice-covered sea is one of the most important tasks in the design of icebreaking ships. To correctly estimate ice load and ice resistance on ship's hull, It is essential to understand the material properties of sea ice during ice field trials and to perform the proper experimental procedure by gathering sea ice data. A measurement of sea ice properties was conducted during February and March of 2012 with the Korean Icebreaking research vessel "ARAON" in the Amundsen Sea, Antarctica. This paper describes a test procedure to obtain sea ice data which provide basic information to estimate ice loads and icebreaking performance of the ship. The data gathered from sea ice field trials during the 2012 Antarctic voyage of the ARAON includes ice temperature/salinity/density and the compressive/flexural strength of sea ice. This paper analyses the gathered Antarctic sea ice material properties comparing with the previous data obtained during ARAON's Arctic and Antarctic voyages in 2010.

• 대한조선학회논문집
• /
• 제42권3호
• /
• pp.284-289
• /
• 2005

A structural design system is developed for the optimum design of double hull tankers based on the multi-objective function method. As a multi-objective function method, Pareto optimal based random search method is adopted to find the minimum structural weight and fabrication cost. The fabrication cost model is developed by considering the welding technique, welding poses and assembly stages to manage the fabrication man-hour and process. In this study, a new structural design is investigated due to the rapidly increased material cost. Several optimum structural designs on the basis of high material cost are carried out based on the Pareto optimal set obtained by the random search method. The design results are compared with existing ship, which is designed under low material cost.

• 유기물자원화
• /
• 제11권2호
• /
• pp.117-124
• /
• 2003

음식물쓰레기 이용 퇴비화의 운전 및 염분저감을 위한 적정조건 검토을 위한 연구를 수행하여 이하의 결과를 얻었다. 음식쓰레기와 톱밥을 7:3, 6:4, 5:5, 4:6, 3:7 비율로 혼합하여 실험한 결과 6:4에서 가장 안정화된 퇴비가 생산될 수 있었다. 한편 음식물쓰레기 : 톱밥의 혼합비가 7:3 및 음식물쓰레기 : 왕겨의 혼합비가 6.5 : 3.5 와 6:4의 경우는 초기 C/N비 자체가 낮게 나타나 적정 퇴비화를 이룩하기 어려웠다. Agent로 톱밥을 혼합한 경우와 왕겨를 혼합한 경우 모두 pH가 급격히 상승하다가 안정화되어 7.5~8.5를 유지하였다. 수분함량은 왕겨를 사용한 경우가 톱밥을 사용한 경우보다 수분감량율이 높게 나타나 톱밥보다 공극율 및 통기성이 원활함을 알 수 있었다. 따라서 톱밥대체제로 이용가능 했다. 탄소화합물 함량은 톱밥의 경우 음식물쓰레기의 혼합 비율이 낮을수록, 왕겨의 경우 음식물쓰레기의 혼합 비율이 높을수록 높았다. 유해성분(납외7종)은 비료기준치 이하를 나타내 안전한 것으로 판별되었다. 염분의 경우 0.43-0.46%을 나타내어 비료기준치(1%)의 1/2로 저감되었다. 이상의 결과를 종합해 보면 음식물쓰레기 퇴비화에 있어 음식물쓰레기와 Agent의 혼합비가 6:4 일 때, Agent로는 왕겨보다 톱밥을 혼합할 때 효율적인 것으로 나타났다.

• 한국환경농학회지
• /
• 제12권3호
• /
• pp.247-254
• /
• 1993

채소류(菜蔬類)의 시설재배(施設栽培)에서 수경재배(水耕栽培)를 대체(代替)할수있는 청정한 배양물질(培養物質)로서 왕겨훈탄의 활용방안을 구명(究明)하기 위하여 산의 종류를 달리하여 왕겨훈탄을 중화(中和)시킨후 몇가지 채소류를 재배하여 생장반응(生長反應)을 비교 검토 하였다. 염산(鹽酸)을 제외한 산(酸) 중화훈탄(中和燻炭)은 채소류(菜蔬類) 재배(栽培)를 위한 배양물질(培養物質)로 활용할수 있을만큼 정상적인 생육(生育)을 보였으며 산(酸) 중화(中和) 처리에 의해 질산태질소의 부가적 공급효과(供給效果)가 있는 질산중화훈탄 처리는 배추, 상치, 및 시금치의 생장량이 퇴비상토 처리보다 양호(良好) 하였다. 염산중화훈탄 처리에서는 특히 상치 및 시금치에서 생육후기(生育後期)에 장해증상(障害症狀)을 보이며 가장 부진한 생육을 나타냈다. 산 중화훈탄 처리에서 자란 식물체중(植物體中)의 화학성분(化學成分)들은 퇴비상토의 경우와 거의 비슷한 함양분포(含量分布)를 보였으며 단백태질소(蛋白態窒素)함량은 오히려 산(酸) 중화훈탄(中和燻炭) 처리들에서 더 높았다. 따라서 채소류(菜蔬類)의 생장과 수확기의 화학성분(化學成分)등을 고려(考慮)할때 질산 중화훈탄은 시설(施設) 채소재배(菜蔬栽培)를 위한 청부(淸浮)한 배양물질(培養物質)로서 활용 가능한 것으로 생각된다.

• Corrosion Science and Technology
• /
• 제14권2호
• /
• pp.59-63
• /
• 2015

Airless spray which is widely used for painting to ship blocks and hull sides is the coating method for attaching atomized paint material to the substrate using spray tip nozzle with compressed air. When the paint material which has high solid contents such as epoxy primer paint is atomized by passing through spray tip nozzle with high pressure, the nozzle composed of tungsten carbide(WC) undergoes the erosive wear, leading to widening of nozzle hole. The deformation of nozzle hole induces improper spray pattern and coating failures such as finger pattern and sagging because the conditions of spray pump pressure and paint flow rate for developing full spray pattern are changed. In this study, an appropriate replacement cycle of spray tip was predicted by measuring the erosive wear tendency as increasing the spraying time of epoxy primer paint.

• Journal of Electrical Engineering and Technology
• /
• 제6권6호
• /
• pp.799-805
• /
• 2011

This study presents three different magnetization models for identifying unknown magnetization of the ferromagnetic thin plate of a ship. First, the forward problem should be solved to accurately predict outboard magnetic fields due to the magnetization distribution estimated at a certain time. To achieve this, three different modeling methods for representing remanent magnetization (i.e., magnetic charge method, magnetic dipole array method, and magnetic moment method) were utilized. Material sensitivity formulas containing the first-order gradient information of an objective function were then adopted for an efficient search of an optimum magnetization distribution on the hull. The validity of the proposed methods was tested with a scale model ship, and field signals predicted from the three different models were thoroughly investigated with reference to the experimental data.

• 한국해양공학회지
• /
• 제26권1호
• /
• pp.1-8
• /
• 2012

To correctly estimate ice load and ice resistance for a ship's hull, it is essential to understand the material properties of sea ice during ice field trials and to use the proper experimental procedure for gathering ice strength data. The first Korean-made icebreaking research vessel (IBRV), ARAON, had her second sea ice trial in the Arctic Ocean during July and August of 2010. This paper describes the test procedures used to properly obtain sea ice strength data, which provides the basic information on the ship's performance in an ice-covered sea and can be used to estimate the correct ice load and ice resistance on the IBRV ARAON. The data gathered from three sea ice field trials during the Arctic voyage of the ARAON includes the ice compressive strength, flexural strength, and failure strain of sea ice. This paper analyzes the gathered sea ice data in comparison with data from the first voyage of the ARAON during her Antarctic Sea ice trial in January 2010.

• Corrosion Science and Technology
• /
• 제7권4호
• /
• pp.197-200
• /
• 2008

In this paper, physical scale modeling was employed to identify the configurations of ICCP system and the electric field signatures. Computational boundary element modeling technique has been used to simulate the performance of the CP system and to predict the associated electric fields signatures. The optimization methods combined with the computer models and physical scale modeling will be presented here, which enable the optimum system design to be achieved both in terms of the location and current output of the anode but also in the location of reference electrodes for impressed current cathodic protection(ICCP) systems. The combined methodology was utilized to determine optimal placement of ICCP components (anodes and reference electrodes) and to evaluate performance of ICCP system for the 2%, 10% and 14% wetted hull coatings loss. The objective is to design the system to minimise the electric field while at the same time provide adequate protection for the ship. The results show that experimental scale modeling and computational modeling techniques can be used in concert to design an optimum ICCP system and to provide information for quickly analysis of the system and its surrounding environment.

• 대한조선학회논문집
• /
• 제48권1호
• /
• pp.42-48
• /
• 2011

To define ice as a solid material, mathematical and physical characteristics and their application examples are investigated for several materials' yield functions which include isotropic elastic, isotropic elastic-plastic, classical Drucker-Prager, Drucker-Prager Cap, Heinonen's elliptic, Derradji-Aouat's elliptic, and crushable foam models. Taking into account brittle failure mode of ice subject to high loading rate or extremely low temperature, isotropic elastic model can be better practicable than isotropic elastic-plastic model. If a failure criterion can be properly determined, the elastic model will provide relatively practicable impact force history from ice-hull interactions. On the other hand, it is thought that the soil models can better predict the ice spalling mechanism, since they contain both terms of shear stress-induced and hydrostatic stress-induced failures in the yield function.

• 방사성폐기물학회지
• /
• 제21권2호
• /
• pp.235-246
• /
• 2023

Neutron resonance transmission technique was applied for assaying isotopic fissile materials produced in the pyro-process. In each process of the pyro-process, a different composition of the fissile material is produced. Simulation was basically performed on ²³⁵U and ²³⁹Pu assay for TRU-RE product, hull waste, and uranium addition. The resonance energies were evaluated for uranium and plutonium in the simulation, and the linearity in the detection response was examined on the fissile content variation. The linear resonance energies were determined for the analysis of ²³⁵U and ²³⁹Pu on the different fissile materials. For enriched TRU-RE assay, the sample condition was suggested; The sample density, content, and thickness are the key factors to obtain accurate fissile content. The detection signal is discriminated for uranium and plutonium in neutron resonance technique. The transmitted signal for fissile resonance has a direct relation with the content of fissile. The simulation results indicated that the neutron resonance technique is promising to analyze ²³⁵U and ²³⁹Pu for various types of the pyro-process material. An accurate fissile assay will contribute toward safeguarding the pyro-processing system.