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>

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

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.

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>

The Great Revival Movement in 1907 and the Korean Church Growth

Yoon Tahk Shon 장로회신학대학교 세계선교연구원 2006 선교와 신학 Vol.18 No.-

하남 동사지 삼층석탑의 구조와 특성 연구

탁경백(Tahk Kyung Baek) 한국중세고고학회 2020 한국중세고고학 Vol.- No.8

일제강점기부터 주목을 받았던 하남 동사지 삼층석탑은 10세기 중후반에 건립된 것으로 알려졌지만, 탑 자체의 구조와 특성에 관한 연구는 충분치 않았다. 이에 본고에서 현재까지 작성된 각종 기록 검토와 삼층석탑 단위부재 검토 및 고려 시대 삼층석탑과의 비교를 통해 동사지 삼층석탑의 구조와 특성을 밝히고자 하였다. 현재까지 기록 중 1965년과 2000년 수리 내용이 삼층석탑의 세부 내용을 알 수 있는 중요한 근거가 되었고, 2017년에 작성된 정밀실측보고서는 단위부재 검토에 기본이 되었다. 또한 고려 시대에 건립된 이중기단을 가진 다른 삼층석탑 62기를 선정하여 기단부와 탑신부 비교를 통해 동사지 삼층석탑의 위상을 검토할 수 있었다. 단위부재 검토 후 고려 시대 석탑과 비교하여 다음과 같은 결과를 확인하였다. 먼저 동사지 삼층석탑과 같이 하층기단부 중 기단석과 면석이 하나의 부재로 구성되는 경우는 28건을 확인할 수 있었다. 또한 안상문이 마련된 탑은 17기로 문양이 유사한 탑은 운산리삼층석탑 등 4기가 확인되었다. 상층기단면석에 우주와 탱주가 마련된 탑도 39건이 확인되어 고려 시대 이중기단을 가진 삼층석탑의 장엄 방법임을 알 수 있었다. 1층 탑신석에 사리공이 마련된 경우는 모두 4건이고 옥개받침의 단수 변화가 같은 것은 나소동삼층석탑 뿐이지만 변화하는 경우는 14건으로 확인되어 일반적인 방식으로 보기는 어렵다. 처마선은 호형으로 된 탑이 43 건으로 확인되어 일반적인 방식으로 판단된다. 이처럼 동사지 삼층석탑은 고려 시대 동형의 석탑과 비교를 통해 일반적인 특징을 가지고 있는 점도 있으나 안상문이나 사리공 마련 등은 다른 탑에서는 찾기 어려운 특성이다. 특히 단위부재에서 재료 수급의 어려움이 보이고 비 규격화된 점은 왕규와 관련성이 있는 것으로 추정된다. The three-story stone pagoda of Dongsaji temple site in Hanam, which has been in the spotlight since the Japanese colonial period, is known to have been built in the mid to late 10th century, but research on the structure and characteristics of the pagoda itself was not sufficient. Accordingly, this study attempted to clarify the structure and characteristics of the three-story stone pagoda by reviewing the various records written in past, reviewing the unit members of the three-story stone pagoda, and comparing it with the three-story stone pagodas of the Goryeo Dynasty. Among the records to date, the repair details in 1965 and 2000 became an important basis for knowing the details of the three-story stone pagoda, and the precision measurement report prepared in 2017 became the basis for the review of unit members. In addition, 62 other three-story stone pagodas with double foundation built in the Goryeo Dynasty were selected, and the status of the three-story stone pagoda of Dongsaji temple site could be reviewed by comparing the foundation and the body. After reviewing the unit member, compared with the stone pagoda of the Goryeo Dynasty, the following results were confirmed. First, there were 28 cases in which the base stone and the face stone were composed of one member of the lower foundation, like the three-story stone pagoda of Dongsaji temple site. In addition, 17 pagodas with Ansang(Elephant-eye) pattern and 4 towers with similar designs were identified, including three-story stone pagoda in Unsan-ri. 39 cases of pagodas with centre pillar and end pillar on the face of upper foundation were also confirmed, indicating that it was a magnificent method of a three-story stone pagoda with a double foundation in the Goryeo Dynasty. There were 4 cases of sacred holes on the first floor body stone, and only three-story stone pagoda in Naso-dong had the same change in the number of ridges, but 14 cases were found to tendency in changing them. So it is difficult to view it in a general way. As for the eaves, 43 pagodas have arc-line, so it was judged in a general way. As described above, the three-story stone pagoda of Dongsaji temple has a general characteristic through comparison with the same type of stone pagodas in the Goryeo Dynasty, but the Ansang(Elephant-eye) pattern and sacred hole arrangements are difficult to find in other pagodas. Particularly, the fact that the material supply and demand was difficult and de-standardized in the unit member was presumed to be related to Wang-gyu.