• Proceedings of the KIEE Conference
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• 2009.07a
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• pp.1737_1738
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• 2009

미사일의 표적 충돌각을 원하는 각도로 제어하는 것은 표적의 취약점을 공략하기 위해 필수적인 기술이다. 표적 타격 지점 및 충돌각을 고려하지 않으면 타격에 성공하였다고 하더라도 표적의 방어 능력이 좋거나 신관이 충돌각에 민감하면 표적의 효과적인 파괴에 실패할 수도 있다. 이런 경우 유도 미사일의 종말 유도 효율을 증가시키기 위해 미사일이 표적을 타격하는 각도인 표적 충돌각(Impact Angle)을 제어할 수 있으면 적정 비행경로의 설정에 유리하고 우회공격 등이 가능할 뿐 아니라 미사일 탄두의 효과를 극대화할 수 있다. 하지만 이러한 장점을 갖는 표적 충돌각 유도 기법에 대한 연구는 아직 활발하게 행해지고 있지는 못하다. 기존 연구 결과들은 2차원 평면상에서의 충돌각 제어만을 다루고 있어, 요와 피치 채널의 커플링 문제가 있는 BTT 미사일에 적용하기가 어렵다는 문제점을 갖고 있다. 또한 미사일 동역학을 무시하거나 단순화하여 문제를 풀고 있기 때문에 실제 상황에 적용이 어렵다는 단점이 있다. 본 논문에서는 3차원 공간상에서의 롤 명령을 모두 포함하면서 동시에 미사일 자동조종제어기, 핀 구동기 동역학을 모두 고려한 새로운 BTT 미사일의 표적 충돌각 유도 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.422-428
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• 2011

In this paper, we introduce system and channel modeling for an underwater ad hoc acoustic network with n regularly located nodes， and then analyze capacity scaling laws based on the model. A narrow-band model is assumed where the carrier frequency is allowed to scale as a function of n. In the network, we characterize in attenuation parameter that depends on the frequency scaling as well as the transmission distance. A cut-set upper bound on the throughput scaling is then derived in extended networks having unit node density. Our result indicates that the upper bound is inversely proportional to the attenuation parameter, thus resulting in a power-limited network. Furthermore, we describe an achievable scheme based on the simple nearest-neighbor multi-hop (MH) transmission. It is shown under extended networks that the MH scheme is order-optimal for all the operating regimes expressed as functions of the attenuation parameter.

• Proceedings of the KAIS Fall Conference
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• 2010.05b
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• pp.634-636
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• 2010

소비자의 행동이론은 경영학의 주된 관심사이다. 소비자의 소비 행동패턴 이론은 소비자의 합리적 소비에 근거한 선호도로써, 선택의 문제를 주요한 연구대상으로 삼고 있다. 하지만 본 모델링은 소비자의 선택을 선호의 문제로 취급하는 기호에 의존하기 보다는, 상권의 측정가능한 크기에 의존하는 수동적 의미의 소비패턴을 산정하게 된다. 단순한 몇 가지 가정을 기반으로 하여 상권이 미치는 영향력을 상권의 거리와 상권의 크기로만 한정할 경우, 최적 경로에 따른 합리적인 소비함수 모델링을 만들 수있다. 상권의 거리 및 상권의 크기로 상권의 범위를 제한 할 경우, 물리학 분야인 전기자기학 중에서 쿨롱의 법칙으로부터 유도된 전기장의 개념을 도입하여 상권의 의미를 재해석할 수 있다. 향후 본 모델링에 대한 소비자 행동패턴의 실질적인 검증 및 추가 도입변수 및 에러항을 도입한 일반적인 모델링으로 발전시킬 수 있고, 그 또한 추가 연구주제가 될 수 있다.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.853-854
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• 2006

Due to a recently developed approach to autopilot controller design for highly-maneuvering BTT (bank-to-turn) missiles, we now can derive explicitly the final-phase optimal guidance (OG) law considering the autopilot dynamics through direct use of the well-known linear optimal control theory. The proposed OG law can decrease the miss distance (MD) remarkably with small acceleration and roll rate profile at the time of interception.

• Journal of the Korean Geotechnical Society
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• v.30 no.9
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• pp.67-75
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• 2014

Methane gas hydrate which is considered energy source for the next generation has an urgent need to develop reliable numerical simulator for coupled THM phenomena in the porous media, to minimize problems arising during the production and optimize production procedures. International collaborations to improve previous numerical codes are in progress, but they still have mismatch in the predicted value and unstable convergence. In this paper, FEM code for fully coupled THM phenomena is developed to analyze methane hydrate dissociation in the porous media. Coupled partial differential equations are derived from four mass balance equations (methane hydrate, soil, water, and hydrate gas), energy balance equation, and force equilibrium equation. Five main variables (displacement, gas saturation, fluid pressure, temperature, and hydrate saturation) are chosen to give higher numerical convergence through trial combinations of variables, and they can analyze the whole region of a phase change in hydrate bearing porous media. The kinetic model is used to predict dissociation of methane hydrate. Developed THM FEM code is applied to the comparative study on a Masuda's laboratory experiment for the hydrate production, and verified for the stability and convergence.

• Journal of the Korean Institute of Intelligent Systems
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• v.13 no.5
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• pp.564-570
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• 2003

This paper presents an adaptive fuzzy control scheme for nonlinear helicopter system which has uncertainty or unknown variations in parameters. The proposed adaptive fuzzy controller is a model reference adaptive controller. The parameters of fuzzy controller are adjusted so that the plant output tracks the reference model output. It is shown that the adaptive law guarantees the stability of the closed-loop system by using Lyapunov function. Several experiments with a small model helicopter having parameter variations are performed to show the usefulness of the proposed adaptive fuzzy controller.

• Journal of Korea Water Resources Association
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• v.40 no.8
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• pp.665-675
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• 2007

An equation is developed to estimate potential groundwater resources available for development. This equation is useful for preliminary planning stages prior to detailed design stages. The equation is a function of major factors such as aquifer characteristics, saltwater intrusion length, coastal groundwater discharge and potential locations of pumping wells. Thus, most important factors are taken into account. The equations are derived using well-known analytical solutions. Thus, the basis is scientifically sound. Use of the equation is quite simple since it is an explicit function of variables. A logical method is proposed to assess a radius of influence of a pumping well considering aquifer characteristics and the pumping rate. Applications to a hypothetical problem and comparison with results from a more rigorous numerical simulation model indicate that results obtained from the proposed equation are conservative.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.9 no.1
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• pp.75-87
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• 2009

We propose in this paper a novel approach to image fusion in which the fusion rule is guided by optimizing an image clarity function. A Genetic Algorithm is used to stochastically select, comparative to the clarity function, the optimum block from among the source images. A novel nested Genetic Algorithm with gifted individuals found through bombardment of genes by the mutation operator is designed and implemented. Convergence of the algorithm is analytically and empirically examined and statistically compared (MANOVA) with the canonical GA using 3 test functions commonly used in the GA literature. The resulting GA is invariant to parameters and population size, and a minimal size of 20 individuals is found to be sufficient in the tests. In the fusion application, each individual in the population is a finite sequence of discrete values that represent input blocks. Performance of the proposed technique applied to image fusion experiments, is characterized in terms of Mutual Information (MI) as the output quality measure. The method is tested with C=2 input images. The results of the proposed scheme indicate a practical and attractive alternative to current multi-focus image fusion techniques.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.59-70
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• 1983

In this paper, it deals with runoff analysis in a mountainous watershed where the concentration time of the river is much Shorter than that of slopes. The momentum and continuity equation are used as the basic expressions and they are solved by the kinematic wave theory. By the introducing the distribution of concentration time, representing the characteristics of topographical and hydraulic factors, into a solution. A response function is derived. Using the optimization technique (simplex Method), the response functions derived in this paper are tested by comparing the observed and the estimated values, and shows promising.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.9
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• pp.613-620
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• 2016

In order to scrutinize the fluid conductivity effects on the electromagnetic flowmeter(EMF) characteristics, a small scale EMF was designed and fabricated. The measuring tube has a $3mm{\times}4mm$ rectangular cross-section, 9 mm length, and a $2mm{\times}3mm$ plate electrode and a ${\Phi}1.5mm$ point electrode. The design parameters, such as the magnetizing frequency and the number of coil turns, and the diameter were optimized. The EMF was tested with a gravimetric calibrator and showed good linearity in the range of 0 to $1.17{\times}10^{-5}m^3/s$. The fluid conductivity was varied between 3 and $11{\mu}S/cm$, and the magnitude of the flow signal was proportional to the fluid conductivity and the wetted area of the electrode. The design information and the test results provide flow measurement techniques for very low flowrate.