• 대한조선학회논문집
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• 제48권6호
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• pp.501-508
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• 2011

In order to control the tip vortex cavitation occurring around the tip of a rotating propeller blade, researches on the propeller cavitation and blade tip vortex flows have been increased. In this paper, the propeller tip vortex flow for a blunt and sharp tips was studied using an unsteady Reynolds-averaged Navier-Stokes equations solver based on a cell-centered finite volume method. In numerical open water test, torques, thrusts, pressure distributions and vortex flows were compared for various rotating speeds. To consider a hull wake, the nominal wake was specified in inlet boundary condition. Pressure distributions and vortex flows with the hull wake were investigated for various propeller rotating angles. From the results, it was confirmed that the blunt tip propeller delayed the tip vortex flow.

• 청정기술
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• 제11권3호
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• pp.153-164
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• 2005

This study found a reliable evaluation for four kinds of pb-Free plating solutions and it's layers, through pure Sn, SnAg, SnBi and SnCu. These four kind of solutions are widely used to pb-Free plating. Hull-cell, Harring-blum, coverage, throwing power, current efficiency, stability, life-time, composition, hardness, roughness, abrasion, scratch, solderability, corrosion, contact angle, morphology, SIR(Surface insulation resistance) and Whisker test were experimented. Also, Using ICP, XRF, FE-SEM, EDS, temperature/humidity chamber, solderability tester, hardness tester, roughness tester, abrasion tester, salt spray tester, contact angle tester, SIR tester, and microscope. In this paper could be shown the systematic and various analysis for reliability about four kinds of pb-Free plating solutions, processes and it's deposit surface.

• Journal of Ship and Ocean Technology
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• 제10권4호
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• pp.1-11
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• 2006

The finite volume based multi-block RANS code, WAVIS developed at MOERI is applied to the numerical self-propulsion test. WAVIS uses the cell-centered finite volume method for discretization of the governing equations. The realizable $k-{\epsilon}$ turbulence model with a wall function is employed for the turbulence closure. The free surface is captured with the two-phase level set method and body forces are used to model the effects of a propeller without resolving the detail blade flow. The propeller forces are obtained using an unsteady lifting surface method based on potential flow theory. The numerical procedure followed the self-propulsion model experiment based on the 1978 ITTC performance prediction method. The self-propulsion point is obtained iteratively through balancing the propeller thrust, the ship hull resistance and towing force that is correction for Reynolds number difference between the model and full scale. The unsteady lifting surface code is also iterated until the propeller induced velocity is converged in order to obtain the propeller force. The self-propulsion characteristics such as thrust deduction, wake fraction, propeller efficiency, and hull efficiency are compared with the experimental data of the practical container ship. The present paper shows that hybrid RANS and potential flow based numerical method is promising to predict the self-propulsion parameters of practical ships as a useful tool for the hull form and propeller design.

• 산업경영시스템학회지
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• 제26권1호
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• pp.1-6
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• 2003

In this paper, we proposed the optimal process conditions on the electro-gilding process. The responses are plating thickness and Sn proportion. The factors are temperature, current density, and addition. We minimized the total number of experiments based on the principle of dividing into small part. We grouped the factors using the plating process information which we already knew. We did Hull Cell test to find relationship between plating solution and electric effects, and applied ANOVA and RSM to estimate the optimal process conditions.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2015년도 추계학술대회
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• pp.37-39
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• 2015

The ships transiting the Northern Sea Route (NSR) have been gradually increased so that the number of ship-ice collision accidents would be increased. The collision between ship and ice floe can lead to serious damage of hulls and decline of ship's maneuverability. In this study, collision tests that a model ship is forced to collide with disk-shaped synthetic ice floes are conducted in a towing tank. The synthetic ice floes made of polypropylene which has similar density with real ice are used. The ice load is measured by a load cell installed on the carriage rod. The ice floe's motion is measured by a motion sensor installed on the synthetic ice floe. The influences of contact conditions such as hull form and ship speed on the ship-ice collision response are investigated and discussed by measured peak force and ice floe's motion.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2007년도 춘계학술발표회 초록집
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• pp.124-125
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• 2007

3가크롬도금 공정 최적화를 위하여 다양한 전기화학적인 기법-즉, Hull cell test, 동전위 분극 실험, 정전류 분극 실험-과 표면 형상 분석이 수행되었다. 3가크롬도금은 용액 pH가 증가함에 따라 조악한 표면 형상을 가졌고, 도금액 온도 증가 시 표면 상 nodule 밀도가 낮아졌다. 본 실험 환경에서 3가크롬도금 공정 최적 조건은 pH2.5-3.0, 온도 $30-40^{\circ}C$, 인가전류밀도 $10-20A/dm^2$이었다.

• 대한조선학회논문집
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• 제50권2호
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• pp.79-87
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• 2013

In this paper, an Euler equation solver based on a Cartesian-grid method and non-uniform staggered grid system is applied to predict the ship motion response and added resistance in waves. Water, air, and solid domains are identified by a volume-fraction function for each phase and in each cell. For capturing the interface between air and water, the tangent of hyperbola for interface capturing (THINC) scheme is used with a weighed line interface calculation (WLIC) method. The volume fraction of solid body embedded in a Cartesian-grid system is calculated by a level-set based algorithm, and the body boundary condition is imposed by volume weighted formula. Added resistance is calculated by direct pressure integration on the ship surface. Numerical simulations for a Wigley III hull and an S175 containership in regular waves have been carried out to validate the newly developed code, and the ship motion responses and added resistances are compared with experimental data. For S175 containership, grid convergence test has been conducted to investigate the sensitivity of grid spacing on the motion responses and added resistances.

• 생태와환경
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• 제41권spc호
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• pp.99-106
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• 2008

본 연구는 왕겨의 메탄을 추출물이 유해 남조 Microcystis aeruginosa 생장에 미치는 영향 및 현장적용 가능성을 조사하였다. 실험에 사용한 왕겨 추출물은 미정제 추출물과 이를 다시 분획하여 분리, 정제한 후 얻은 ${\beta}$-sitosterol, ${\beta}$-sitosterol-${\beta}$-D-glucoside, 1-tetratriacontanol, hentriacontane, orizaterpenoid, stigmas-5-en-$3{\alpha}$ 26-diacetate, stearic acid, myristic acid 등 8가지의 순수화합물로서, 이들 추출물을 남조 세포에 처리하여 생장 변화를 조사하였다. 연구에 사용된 조류는 국립환경과학원에서 분양 받은 M. aeruginosa (NIER 10010)이고, 물벼룩은 독일 BBE사에서 분양 받은 Daphnia magna로서, 이들은 각각 CB배지와 경수를 이용하여 배양 유지되었다. 왕겨 메탄을 추출물을 1, 10, 100, $1,000{\mu}g\;L^{-1}$의 농도로 처리하여 조류 배양조건과 동일한 조건에서 일정시간 배양하였다. 실험결과, 왕겨 메탄을 추출물은 모든 처리구에서 7일 후 $59{\sim}73%$의 높은 생장 억제 효과를 나타내며 M. aeruginosa의 생장을 억제하였다. 한편, 8가지 물질을 M. aeruginosa에 $1,000{\mu}g\;L^{-1}$ 농도로 처리한 실험에서는 3가지 물질 (${\beta}$-sitosterol-${\beta}$-D-glucoside, hentriacontane, orizaterpenoid)에서 생장 억제 효과를 보였다. 또한 M. aeruginosa에 이들 3가지 물질을 조합하여 실험한 결과, 이들 3가지를 혼합한 처리구에서 생장 억제에 대한 유의한 상승효과를 나타냈다(p<0.05). 왕겨 메탄올 추출물의 현장적용 가능성을 파악하고자 $1,000{\mu}g\;L^{-1}$의 추출물 농도에 물벼룩을 처리하여 실험한 결과, 96시간 후에 85%의 높은 생존율을 보였다. 결론적으로, 왕겨 추출물은 M. aeruginosa의 생장 억제에 효과적인 천연물질로서 조류 제어에 상승작용이 나타났으며, 현장 적용시 수중생물에 대한 독성은 높지 않을 것으로 판단되었다.