• 선박안전
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• 제5권
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• pp.30-40
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• 2000

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2010년도 춘계 학술논문 발표대회 1부
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• pp.77-81
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• 2010

This study deals with the analysis of color-difference and physical property of anti-corrosion coatings using at inside of concrete tank for drinking water. Because anti-corrosion coatings are effected by chemical attack, color and physical property are changed. So in this study when epoxy resin coatings of 3 types were received chemical attack by Cl- and NaOH, we present the co-relationship between color-difference and bond strength. For this study, we used the colorimetry, which can measure the degree of color difference on surface of materials. As the results, in case of Cl-, color change is appeared, bond strength also is decreased. From this experiment, we could know that color change due to chemical aging has the deep relationship with physical performance(bond strength) materials. further researches are needed.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.127-135
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• 2006

We analyzed recyclability of the fuel tanks made from steel or aluminum alloy. For a comparison of the fuel tank recyclability, first we had analyzed the process of disassembly in a vehicle and evaluated its disassemblability. Then we evaluated the recyclability for reuse and withdrawal. The processes were more or less same owing to the similarity of fastening method of fuel tank and components. However, the fuel tank of the aluminum alloy was easier (about 5%) to disassembly than the fuel tank of steel. This could be attributed to the differences in weight of steel and aluminium. On light of the withdrawal and reuse, the fuel tank made up of steel needed to plate with zinc or lead due to its anti-corrosiveness. Hence, it required additional processes. In this paper, we were explaining the results of our on going research on the recyclability of fuel tanks made of steel and aluminum alloys. The differences that we found between the fuel tank made up of the aluminum alloy and steel were in their weight, recyclability, disassemblability, anticorrosive property, cost and productivity.

• Structural Engineering and Mechanics
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• 제68권1호
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• pp.1-15
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• 2018

In ocean industry, free surface type ART (Anti Roll tank) system has been widely used to suppress the roll motion of floating structures. In those, various obstacles have been devised to obtain the sufficient damping and to enhance the controllability of freely rushing water inside the tank. Most of previous researches have paid on the development of simple mathematical formula for coupled ship-ARTs analysis although other numerical and experimental approaches exist. Little attention has been focused on the use of 3D panel method for preliminary design of free surface type ART despite its advantages in computational time and general capacity for hydrodynamic damping estimation. This study aims at developing a potential theory based hydrodynamic code for the analysis of floating structure with baffled ARTs. The sloshing in baffled tanks is modeled through the linear potential theory with FE discretization and it coupled with hydrodynamic equations of floating structures discretized by BEM and FEM, resulting in direct coupled FE-BE formulation. The general capacity of proposed formulation is emphasized through the coupled hydrodynamic analysis of floating structure and sloshing inside baffled ARTs. In addition, the numerical methods for natural sloshing frequency tuning and estimation of hydrodynamic damping ratio of liquid sloshing in baffled tanks undergoing wave exiting loads are developed through the proposed formulation. In numerical examples, effects of natural frequency tuning and baffle ratios on the maximum and significant roll motions are investigated.

• 어선
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• 제44권
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• pp.9-17
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• 1990

• 한국항해항만학회지
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• 제34권4호
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• pp.271-279
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• 2010

The Mobile Harbor(MH) is a new transportation platform that can load and unload containers to and from very large container ships in the sea. This loading and unloading by crane can be performed with only very small movements of the MH in waves because MH is operated outside of the harbor. For this reason, an anti-rolling tank(ART) and an active mass driving system(AMD) were designed to reduce MH's roll motion, especially at the natural frequency of MH. In the conceptual design stage, it is difficult to confirm the design result of theses anti-rolling devices without modeling and simulation tools. Therefore, the coupled MH and anti-rolling devices' dynamic equations in waves were derived and a simulation program that can analyze the roll reduction performance in various conditions, such as sea state, wave direction, and so on, was developed. The coupled equations are constructed as an eight degrees of freedom (DOF) motion that consists of MH's six DOF dynamics and the ART's and AMD's control variables. In order to conveniently include the ART's and AMD's control dynamics in the time domain, MH's radiated wave force was described by an impulse response function derived by the damping coefficient obtained in the frequency domain, and wave exciting forces such as Froude-Krylov force and diffraction force and nonlinear buoyancy were calculated at every simulation time interval. Finally, the roll reduction performances of the designed anti-rolling devices were successfully assessed in the various loading and wave conditions by using a developed simulation program.

• 한국항공우주학회지
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• 제42권1호
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• pp.76-81
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• 2014

군용 헬리콥터는 적 지역에 침투 시 저공비행 및 침투비행으로 인해 적의 소형화기에 노출되면서, 피탄에 의한 항공기의 폭발 유발 가능성이 높다. 최근 군요구도에 있어서 피탄에 의한 폭발 환경에 대해서 생존성 확보를 위한 내탄 성능을 요구한다. 국내 최초의 군용 헬리콥터인 한국형기동헬기의 연료계통 요구도에도 적의 피탄에 대한 내폭발성을 요구하고 있으며, 요구도 충족을 위해 국내 최초로 탑재형 불활성 가스발생장치(OBIGGS)를 적용하였다. 개발단계에서 미흡하게 설계된 내폭발성과 연관된 Vent System을 개선하여 내폭발성 성능을 재평가하고 설계에 적합함을 입증하였다.

• 한국군사과학기술학회지
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• 제21권1호
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• pp.47-60
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• 2018

In this paper, we proposed a method for eliminating aiming error of unguided anti-tank rocket using improved target tracking. Since predicted fire is necessary to hit moving targets with unguided rockets, a method was proposed to estimate the position and velocity of target using fire control system. However, such a method has a problem that the hit rate may be lowered due to the aiming error of the shooter. In order to solve this problem, we used an image-based target tracking method to correct error caused by the shooter. We also proposed a robust tracking method based on TLD(Tracking Learning Detection) considering characteristics of the FCS(Fire Control System) devices. To verify the performance of our proposed algorithm, we measured the target velocity using GPS and compared it with our estimation. It is proved that our method is robust to shooter's aiming error.

• 한국군사과학기술학회지
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• 제24권1호
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• pp.133-143
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• 2021

In government procurement programs, cost estimation and analysis support funding decisions and are the basis for other major decisions, too. Such estimating and analyzing the cost of the weapon systems are crucial in execution of the defense budget. However, existing cost estimations and analyses have focused on domestic R&D projects, thus those are not valid in application to foreign weapon acquisitions. This study aims at foreign weapon systems that are acquired from Direct Commercial Sales. Because the data for price estimation of a foreign weapon is usually not available, we suggest a price estimation model based on performance factors of the weapon. In this study, the proper price of the weapon system is estimated using the parametric cost estimating model. Using the data of helicopter-launched anti-tank guided missiles worldwide, we analyze the effect of each performance factor on the weapon system price by regression analysis, and use step-wise and ridge regression analysis to remove multi-collinearity. This study hopefully contributes to more reasonable decision making on proper price of weapons.

• 동력기계공학회지
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• 제17권2호
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• pp.95-102
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• 2013

For vessels operating in the cold climate regions, the ballast water inside or hopper tanks above the waterline may be frozen, starting at the top of the tank and at the side walls. Therefore, countermeasures against freeze-up of the ballast tank such as air-bubbling system, hot steam injecting system, heating coil system and water circulating system are taken to prevent freeze-up phenomenon; however, there are no rigorous investigations of anti-freezing to examine the effectiveness and validity of systems against freeze-up of the ballast tank, in which the temperatures are about $-25^{\circ}C$ (ambient air temperature) and $0^{\circ}C$ (sea water), respectively. In this paper, to ensure reasonable specifications for cold regions if the measures from the above-mentioned systems against freeze-up are effective, the phenomenon of ballast tank freeze-up is simulated and discussed in low temperature conditions. With the results using the commercial CFD code, CFX 14, the most cost-effective solution is conducted to prevent being frozen along the outer surface.