• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.42 no.1
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• pp.20-28
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• 2014

In this paper, based on the characteristics of proportional navigation, a composite guidance law is proposed for impact angle control of passive homing missiles maintaining the lock-on condition of the seeker. The proposed law is composed of two guidance commands: the first command is to keep the look angle constant after converging to the specific look angle of the seeker, and the second is to impact the target with terminal angle constraint and is implemented after satisfying the specific line of sight(LOS) angle. Because the proposed law considers the seeker's filed-of-view(FOV) and acceleration limits simultaneously and requires neither time-to-go estimation nor relative range information, it can be easily applied to passive homing missiles. The performance and characteristics of the proposed law are investigated through nonlinear simulations with various engagement conditions.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.43 no.6
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• pp.497-506
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• 2015

A composite guidance law for impact angle control against nonstationary nonmaneuvering targets is proposed. The proposed law is based on the characteristics of proportional navigation and generates two kinds of guidance commands during the homing phase. The first command is to keep the desired look angle, and the second is to attack the target with impact angle constraint. The switch of guidance phases occurs when the specific light-of-sight(LOS) angle determined from the engagement information is satisfied. The calculation method of the maximum achievable impact angle is also proposed to design easily the desired impact angle within the missile capability. Numerical simulations are performed to investigate the performance and characteristics of the proposed law.

• Proceedings of the Korean Society For Composite Materials Conference
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• 1999.11a
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• pp.111-117
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• 1999

섬유강화 복합재료의 섬유와 수지까지 세부적으로 모델링이 가능한 Direct Numerical Simulation을 통해서 Boron/Aluminum 섬유강화 복합재료의 탄성계수들을 구해 보았다. 수치실험에서는 복합재료를 직교이방성 물질로 가정하였고, 특정 체적에 대한 평균치를 이용해서 물성치를 구하였으며, 혼합법칙에 의해서 구한 값 및 대표체적요소(Representative Volume Element)를 사용해서 구한 값들과 비교하였다. 혼합법칙의 경우, 섬유방향 인장계수(E₁)을 제외한 나머지 물성치들에 대해서는 상당한 차이를 나타내며, 이는 혼합법칙 유도과정에서 가정한 기본가정들이 적절하지 않기 때문이라는 것을 수치실험(Numerical Experiment)을 통해 알 수 있었다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.11
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• pp.1417-1423
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• 2020

This paper proposes a waypoint guidance algorithm for the Autonomous Underwater Vehicle(AUV). The proposed simplified guidance algorithm is presented, which is combined LOS guidance and cross-track guidance for path following. Cross-track error is calculated using the position of the AUV and reference path. LOS guidance and cross-track guidance are appropriately changed according to cross-track error. And the stability of the system has been improved using variable cross-track control gain by cross-track error. Also, in this paper, navigation hardware in-the loop simulation(HILS) is implemented to verify navigation algorithm of AUV that performs combined navigation using inertial navigation device and doppler velocity log(DVL). Finally, we design integrated system HILS (including navigation HILS) for performance verification of guidance algorithm of the autonomous underwater vehicle. By comparing the sea test result with HILS result, the proposed guidance algorithm and HILS configuration were confirmed be correct.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.21 no.48
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• pp.153-164
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• 1998

본 논문은 2-상태 시스템의 신뢰도 계산을 위하여 Heidtmann[3]이 제시한 가역 알고리즘을 부울 대수를 사용하여 경로집합으로부터 절단집합을 유도하거나, 역으로 절단집합으로부터 경로집합을 유도함으로서 효율성을 입증하였으며, 포함-불포함 공식(inclusion-exclusion formula)과 추축 분해법칙(pivotal decomposition rule)을 이용하여 직·병렬구조 및 복합구조의 신뢰도를 계산할 수 있는 알고리즘을 개발, 분석하였다.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.117-120
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• 1995

분수차 퓨리에(Fouier) 변환은 퓨리에 면환을 일반화시킨 것으로, 위치와 공간주파수의 복합적인 표현을 주나, 한 개의 렌즈를 광학적 구현이 역시 가능하다. 광신호처리에서 많이 사용되는 정합 필터를 구성하는 퓨리에 면환을 각각 분수차로 일반화시킴으로서, 위치 필터와 공간주파수 필터의 특성이 복합된 새로운 필터를 구성할 수 있게 된다. 이 필터 구조는 신경회로망의 학습으로 대치된다. 최대경사법과 오차역전파(error back-propagation)에 기초한 학습 법칙이 유도되고, 컴퓨터 시뮬레이션 결과가 제시된다.

• Composites Research
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• v.34 no.2
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• pp.123-128
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• 2021

This paper dealt with multi-scale natural frequency characteristics of wavy CNT (carbon nanotube) reinforced composites by applying the Mori-Tanaka method, rule of mixture, and Halpin-Tsai equation. By compelling benefit of an ad-hoc Eshelby tensor, the load-transfer characteristics of CNT with a waviness implanted in the polymer matrix was determined. The numerical results obtained are in good agreement with those reported by other investigators. Furthermore, the new results reported in this paper show the interactions between CNT weight, waviness ratios and layup sequences of laminated composites. Key observation points are discussed and significant considerations are given in practical designing of CNT reinforced composites.

• Composites Research
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• v.33 no.2
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• pp.81-89
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• 2020

In this review paper, we introduce recent research studied effective physical properties of the reinforced composite using mean-field homogenization. We address homogenization for effective stiffness and expand it to effective thermal/electrical conductivity and dielectric constant. Multiphysics problems like piezoelectricity and thermoelectricity are considered by simplifying the constitutive equation into the linear equations like Hooke's law. We present a generalized theoretical formula for predicting effective physical properties of composite and validation by against finite element analysis.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.68 no.4
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• pp.566-572
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• 2019

This paper proposes a new composite guidance law that can intercept moving targets and satisfy look angle rate constraint. In order to obtain the composite guidance law, we first develop a new look angle rate control guidance law which can maintain the maximum look angle rate limitation. And then, we propose the composite guidance scheme on the basis of the look angle rate control guidance and the proportional navigation guidance. To investigate the capturablity and characteristics of the proposed guidance, we also derive closed-form solutions and perform various numerical simulations. The proposed composite guidance only requires the line-of-sight rate, closing velocity, and missile's speed, thereby easily implementing in practical homing missiles.

• Science of Emotion and Sensibility
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• v.27 no.3
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• pp.83-88
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• 2024

This study aims to explore the effect of combined stimulation consisting of relaxation-inducing scent and high-concentration oxygen on psychological/physiological responses. The cerebral blood flow responses and arousal that occur when oxygen concentration is controlled under the same scent conditions were observed. The experiment's scent was lavender oil (relaxing scent), and the oxygen concentrations were normal (21%) and high (30%). The experiment involved 12 male adults repeating a 5-minute rest period and a 5-minute stimulation period. The hemoglobin (HbO) concentration was extracted using the Beer-Lambert law to observe cerebral blood flow responses. Arousal was assessed using a 5-point scale questionnaire. A paired t-test was used to compare the two stimuli (lavender +21%, lavender +30%). Results reveal that HbO concentration in the frontal lobe increased, whereas arousal decreased at lavender +30% vs. lavender +21%. These results suggest that adding high-concentration oxygen to scent stimulation can induce more brain activation and relaxation.