추적-회피 게임 기반 유도법칙의 성능 분석

김영삼(Young-Sam Kim),탁민제(Min-Jea Tahk),유혁(Hyeok Ryu) 한국항공우주학회 2008 韓國航空宇宙學會誌 Vol.36 No.8

본 논문에서는 추적-회피 게임의 해를 기반으로 한 유도법칙을 제안하고, 성능을 분석한다. 추적자를 유도하는데 게임 해의 초기 값을 사용하고, 다음 단계에서 추적-회피 게임의 해를 다시 계산한다. 이 점에 있어서 제안된 유도법칙은 모델예측제어와 유사하다. 회피자가 요격시간을 최대화하는 방향으로 항상 기동하는 추적-회피 시나리오에 대하여, 비례항법유도와 비교한 결과, 제안된 유도기법이 더 넓은 요격영역을 가진다는 것을 확인하였다. We propose a guidance law based on pursuit-evasion game solutions, and analyze its performance, The game solutions are obtained from the pursuit-evasion game solver developed by Tahk. The initial value of the game solution is used for guidance, and then the pursuit-evasion game is solved again at the next time step. In this respect, the proposed guidance laws are similar to the approach of model predictive control. The proposed guidance method is compared with proportional navigation guidance for a pursuit-evasion scenario, in which the evader always tries to maximize the capture time. According to the comparison, it has larger a capture set than ones of proportional navigation guidance law.

Rapid large area fabrication of multiscale through-hole membranes

Tahk, D.,Paik, S. M.,Lim, J.,Bang, S.,Oh, S.,Ryu, H.,Jeon, N. Royal Society of Chemistry 2017 Lab on a chip Vol.17 No.10

<P>There are many proposed mechanisms by which single cells can be trapped; among them is the through-hole membrane for the characterization of individual microorganisms. Due to the small scale of the fabricated pores, the construction of through-hole membranes on a large scale and with relatively large areas faces many difficulties. This paper describes novel fabrication methods for a large-area, freestanding micro/nano through-hole membrane constructed from versatile membrane materials using through-hole membranes on a microfluidic chip (THMMC). This process can rapidly (< 20 min) fabricate membranes with high fidelity multiscale hole size without residual layers. The through-hole site was easily customizable from the micro to the nanoscale, with a low or high aspect ratio giving rise to reliable membranes. Also, the rigidity and biocompatibility of the through-hole membrane are easily tunable by simple injection of versatile membrane materials to obtain a large area (up to 3600 mm(2)). Membranes produced in this manner were then applied as a proof of concept for the isolation, cultivation, and quantification of individual micro-algal cells for selection with respect to the growth rate, while controlling the quorum sensing mediated metabolic and proliferative changes.</P>

A Study on the Fault Diagnosis of Roller-Shape Using Frequency Analysis of Tension Signals and Artificial Neural Networks Based Approach in a Web Transport System

Tahk, Kyung-Mo,Shin, Kee-Hyun The Korean Society of Mechanical Engineers 2002 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.16 No.12

Rollers in the continuous process systems are ones of key components that determine the quality of web products. The condition of rollers (e.g. eccentricity, runout) should be consistently monitored in order to maintain the process conditions (e.g. tension, edge position) within a required specification. In this paper, a new diagnosis algorithm is suggested to detect the defective rollers based on the frequency analysis of web tension signals. The kernel of this technique is to use the characteristic features (RMS, Peak value, Power spectral density) of tension signals which allow the identification of the faulty rollers and the diagnosis of the degree of fault in the rollers. The characteristic features could be used to train an artificial neural network which could classify roller conditions into three groups (normal, warning, and faulty conditions) The simulation and experimental results showed that the suggested diagnosis algorithm can be successfully used to identify the defective rollers as well as to diagnose the degree of the defect of those rollers.

Impact Time Control Based on Time-to-Go Prediction for Sea-Skimming Antiship Missiles

Tahk, Min-Jea,Shim, Sang-Wook,Hong, Seong-Min,Choi, Han-Lim,Lee, Chang-Hun IEEE 2018 IEEE transactions on aerospace and electronic syst Vol.54 No.4

<P>This paper proposes a novel approach for guidance law design to satisfy the impact-time constraints for a certain class of homing missiles. The proposed guidance law provides proper lateral acceleration commands that make the impact time error converge to zero by the time of impact. This scheme can be applied to any existing guidance law for which a formula of predicted time to go is available. Convergence of time-to-go errors is supported by Lyapunov stability. The optimal guidance law and the impact angle control guidance law are extended by the proposed method for impact-time-control guidance and impact-time-and-angle-control guidance, respectively. The performance of the extended guidance laws is demonstrated by numerical simulation.</P>

Perch Landing Assisted by Thruster (PLAT): Concept and Trajectory Optimization

Tahk, Min-Jea,Han, Seungyeop,Lee, Byung-Yoon,Ahn, Jaemyung The Korean Society for Aeronautical and Space Scie 2016 International Journal of Aeronautical and Space Sc Vol.17 No.3

A concept of the perch landing assisted by thruster (PLAT) for a fixed wind aircraft is proposed in this paper. The proposed concept is applicable to relatively large unmanned aerial vehicles (UAV), hence can overcome the limitation of existing perch landing technologies. A planar rigid body motion of an aircraft with aerodynamic and thruster forces and moments is modeled. An optimal control problem to minimize the fuel consumption by determining the histories of thruster and elevator deflection angle with specified terminal landing condition is formulated and solved. A parametric study for various initial conditions and thruster parameters is conducted to demonstrate the practicability of the proposed concept.

Augmented Polynomial Guidance with Terminal Speed Constraints for Unpowered Aerial Vehicles

Tahk, Min-Jea,Moon, Gun-Hee,Shim, Sang-Wook Springer-Verlag 2019 International Journal of Aeronautical and Space Sc Vol.20 No.1

Hessian approximation algorithms for hybrid optimization methods

Tahk, Min-Jea,Park, Moon-Su,Woo, Hyun-Wook,Kim, Hyoun-Jin Informa UK (TaylorFrancis) 2009 Engineering optimization Vol.41 No.7

A hybrid optimization method of evolutionary and gradient search

Tahk, Min-Jea,Woo, Hyun-Wook,Park, Moon-Su Gordon and Breach 2007 Engineering optimization Vol.39 No.1

<P> This article proposes a hybrid optimization algorithm, which combines evolutionary algorithms (EA) and the gradient search technique, for optimization with continuous parameters. Inheriting the advantages of the two approaches, the new method is fast and capable of global search. The main structure of the new method is similar to that of EA except that a special individual called the gradient individual is introduced and EA individuals are located symmetrically. The gradient individual is propagated through generations by means of the quasi-Newton method. Gradient information required for the quasi-Newton method is calculated from the costs of EA individuals produced by the evolution strategies (ES). The symmetric placement of the individuals with respect to the best individual is for calculating the gradient vector by the central difference method. For the estimation of the inverse Hessian matrix, symmetric Rank-1 update shows better performance than BFGS and DFP. Numerical tests on various benchmark problems and a practical control design example demonstrate that the new hybrid algorithm gives a faster convergence rate than EA, without sacrificing the capability of global search.</P>

政治參與란 무엇인가?

卓鎭煥(Tahk, Jin Hwan) 전북대학교 법학연구소 1981 法學硏究 Vol.8 No.-

언어네트워크분석을 통한 국내 과학관 연구 동향 분석

탁현수(Tahk, Hyun Soo),김홍정(Kim, Hong Jeong) 한국전시산업융합연구원 2015 한국과학예술융합학회 Vol.22 No.-

한국의 과학관은 서양에서의 과학박물관 개념과 과학센터 개념을 모두 가지고 있어, 국내의 과학관 연구는 크게 과학사물을 수집하여 발굴하고 연구하는 분야와 과학기술을 전시하고 교육하는 분야로 구분할 수 있다. 과학관 연구는 과학관 현장의 바람직한 변화를 위해 과학관 건립, 정책연구, 순수과학기술, 전시, 교육, 과학기술사, 자연사 등 매우 다양한 분야에서 다루어왔으나, 학술적 논의는 충분하지 못하였다. 이 연구의 목적은 국내 학술지에 게재된 과학관 연구논문을 분석하여 한국 과학관 연구의 현황을 살펴봄으로써 과학관 발전을 위한 연구 시사점을 제공하는 것이다. 연구대상은 2015년 9월까지 한국교육학술정보원의 학술연구정보서비스(RISS)에서 ‘과학관’을 주제어로 검색 가능한 KCI등재지, KCI등재후보지로 선별하였다. 분석방법은 연도별, 학술지별, 학술분야별 논문 게재 수에 대해 기술통계분석을 실시하였으며, 논문의 주제어를 기반으로 주요단어 및 공출현단어의 빈도를 지도화하는 언어네트워크분석을 수행하였다. 연구결과, 2005년부터 2015년 9월까지 게재된 과학관 연구논문은 26종 학술지에서 59편이 게재되었으며, 4편 이상의 논문을 게재한 한국과학예술포럼, 한국과학교육학회, 한국실내디자인학회논문집, 한국지구과학학회지, 한국공간디자인학회논문집 등 이들 5개 학술지에서 전체 대비 50%가 넘는 논문을 발표하였다. 학술분야로 살펴보면, 과학관 연구는 사회과학과 복합학으로 분류된 학술지에서 발표되었으며, 각각 교육학과학제간 연구에 대한 비중이 높았다. 또한, 과학관 연구에서 사용 빈도가 높은 단어는 ‘과학관’, ‘전시’, ‘교육’, ‘학습’, ‘과학교육’, ‘비형식’ 등이었으며, [‘과학관’-‘전시’-‘학습’], [‘과학관’-‘전시’-‘패널’], [‘과학관’-‘전시’-‘비형식’] 등이 공출현하는 소규모 언어네트워크를 가졌다. 이 같은 연구결과는 지금까지 과학관 연구가 학술적으로 양적인 증가를 나타내면서 전시 또는 교육에 초점을 두어왔음을 보여준다. 그러나 과학관 현장에서는 과학기술콘텐츠연구, 표본과 같은 소장품의 보존처리연구를 바탕으로 한 전시기획 및 전시운영 등과 같은 연구결과들을 요구한다는 점을 고려할 때, 과학관 연구는 학술적으로 보다 다양한 주제로 확대될 필요가 있음을 시사한다. Science museums in Korea display two divergent roles: as science museums and science centers. Therefore, research into Korean science museums often focuses on either collecting, discovering and studying scientific objects, or exhibition of and education about scientific technologies. For the improvement of science museums, there has been numerous research undertaken into science museums in Korea regarding policy, pure scientific technology, exhibition, education, the history of science technology, natural history and the foundation of a new science museum. However, these topics have yet to be discussed from an academic perspective. The purpose of this study is to examine Korean journals related to science museums in order to analyze research trends into science museums, and to interpret the implications for the development of science museums in Korea. The subject of the study is the level of Korean Citation Index (KCI-listed, KCI listing candidates), that can be searched by the key phrase, "science museum" in Korean language through the RISS service. In this study, the Descriptive Statistical Analysis Method is utilized to discover the number of research articles, classifying them by year, type and field of research. Also, the Language Network Analysis was conducted to map the frequency of key words and co-occurrence words throughout a variety of research articles. The results show that 59 research papers were published in 26 journals from 2005 to September 2015. Specifically, the five major journals published more than 50% of the total papers. In relation to research fields, the study of science museums is mostly dealt with in the journals of social science and interdisciplinary science. In addition, key phrases, such as "science museum", "exhibition", "education", "learning", "science education" and "informal" are the most frequently used among the research studies. Finally, there are small language networks that appear concurrently as below: [science museum-exhibit-learning], [science-exhibit-panel], [science museum-exhibit-informal]. These results show that studies into science museums have focused on exhibition and education, by enhancing their quantity of research. However, a broader scope of research into science museums appears to be necessary, due to the fact that more research into exhibition planning and operations based on science and technology and conservation are so crucial in the practical field.