시간 지연 적응 백스텝핑 제어를 이용한 유도탄의 가속도 제어기 설계

서민국,이창훈,탁민제 한국항공우주학회 2012 한국항공우주학회 학술발표회 논문집 Vol.2012 No.4

본 논문에서는 공기 역학적 비선형성을 가지고 있고 꼬리 날개에 의한 비최소위상 시스템이 되는 유도탄의 종축 가속도 제어 문제를 다룬다. 공기 역학적 비선형성 문제의 해결을 위해 하나의 트림상태에서의 선형 운동방정식을 이용하여 제어기를 설계한 후 시간 지연 적응 제어 기법으로 트림상태의 변화에 의해 발생하는 모델 오차를 보상해 준다. 또한 비최소위상 문제에 대해서는 백스텝핑제어기를 이용한 내부루프 받음각 제어기와 PI 제어기로 구성된 외부루프 가속도 제어기로 구성된 종속구조를 제안하고자 한다. 마지막으로 제안된 제어기의 성능을 시뮬레이션을 통하여 검증한다. Normal acceleration control problem of a missile, which is non-minimum phase system due to tail fin, with aerodynamic nonlinearity is covered in this paper. In order to handle the aerodynamic nonlinearity problem, a controller using a linear dynamic equation near one trim point is designed and time-delay adaptive control law is applied to it for error reduction. A cascade form of control structure, which has an angle-of-attack controller with back-stepping controller structure as inner loop and an acceleration controller with PI controller structure as outer loop, is suggested to deal with non-minimum phase problem. Simulation results to check the performance of the suggested controller are presented at the end of this paper.

Ptolemy II를 이용한 유도탄 자동 조종 시뮬레이션 모델 개발

서민국,이창훈,탁민제,이진익,전병을 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.4

본 논문에서는 시뮬레이션 소프트웨어인 Ptolemy II 를 소개하고, 이를 이용한 유도탄 자동 조종 시스템의 시뮬레이션 모델 개발을 다룬다. Ptolemy II 는 계층적 모델 구성, 그리고 클래스 및 상속 개념과 같이 복잡한 시스템의 모델링에 도움이 되는 특징들을 포함하고 있다. 뿐만 아니라, 새로운 행동자를 개발함으로써 그 기능을 확장시키는 것이 가능하다. 이러한 Ptolemy II 의 특징들을 활용하여 유도탄 자동 조종 시뮬레이션 모델을 개발하였으며, 그 성능 검증을 위한 시뮬레이션이 수행되었다. In this paper, Ptolemy II, which is simulation software, is introduced, and a simulation model of missile autopilot system is developed with this software. Ptolemy II has characteristics, like hierarchical modeling and the concept of class and inheritance, which are helpful for modeling of complex systems. Moreover, it is possible to expand the function of Ptolemy II by developing new actors. By utilizing these features of Ptolemy II, missile autopilot simulation model was constructed, and simulations to evaluate its performance were carried out.

손상선박의 예인특성 평가를 위한 모형시험 및 수치해석 연구

서민국,김남우,이용국,홍사영,최혁진 해양환경안전학회 2021 해양환경안전학회 학술발표대회 논문집 Vol.2021 No.11

등방성 운동에너지 탄두의 형태에 따른 구성 요소 배열 및 관통자 전개 특성 분석

서민국,심상욱,홍성민,탁민제,이진익,송경록 한국항공우주학회 2014 한국항공우주학회 학술발표회 논문집 Vol.2014 No.4

본 논문에서는 등방성 운동에너지 탄두의 두 가지 형태인 Jellyroll 탄두와 Central Core 탄두의 내부구성 요소 배열 및 관통자 전개 특성에 대한 비교 분석을 다룬다. 두 탄두 형태에 대하여 탄두에 포함된 각 내부 구성 요소의 총 질량 및 전체 탄두 질량을 정량적으로 계산하는 방법이 고안된다. 또한 각 탄두 형태의 관통자 전개 형상을 사출 속력 모델을 통하여 분석한다. 시뮬레이션을 통하여 Jellyroll 탄두와 Central Core 탄두의 구성 상의 특성 및 관통자 전개 형태를 비교한다. In this paper, a comparison analysis on component configurations and rod deployment characteristics of two different isotropic rod warhead types, jellyroll warhead and central core configuration warhead, is handled. Total mass of each component included in a warhead and total warhead mass are quantitatively calculated for two types of warheads. Also, the rod deployment pattern of each warhead type is analyzed with rod ejection velocity models. Simulations are conducted to compare the compositional characteristics and rod deployment patterns of jellyroll warhead and central core warhead.

조리과 교수의 생애사에 따른 국내 서양조리교육 발전과정: 생태학적 체계 이론을 중심으로

서민국,정라나 한국외식경영학회 2023 외식경영연구 Vol.26 No.4

This study aimed to investigate the future trajectory of Western culinary education development in South Korea by examining the life story of a Culinary Arts Professor and exploring the transformation of Western culinary education from an ecological standpoint. To achieve this, the Culinary Arts Professor was selected as the focal point of the life story research. Data were collected through eight interviews and participatory observations, and subsequently analyzed using longitudinal coding techniques. The findings revealed that the advancement of Western culinary education in South Korea should prioritize diversification through the synergy of industry and education, the adoption of future-oriented learning platforms to facilitate interdisciplinary integration, and the cultivation of well-rounded talents with cognitive, moral, and behavioral competencies. This study is expected to contribute to the reconceptualization and determination of the developmental direction for Western culinary education in South Korea.

Segregation Behavior of Poly(butyl acrylate)-b -Poly(methyl methacrylate-r-styrene) Depending on Comonomer Compositions

서민국,이상인,허준,백현종 한국고분자학회 2018 한국고분자학회 학술대회 연구논문 초록집 Vol.43 No.2

시선각 측정 기반 표적 상태변수 추정의 가관측성 향상을 위한 수정 적응 단속 기동 설계

서민국,탁민제 한국항공우주학회 2013 한국항공우주학회 학술발표회 논문집 Vol.2013 No.11

본 논문에서는 시선각만을 측정하여 표적 상태변수를 추정하는 시스템의 가관측성을 향상시키는 기법에 대하여 논의한다. 적응 단속 기동은 시선각 변화율 크기를 일정 수준 이상으로 유지함으로써 가관측성 존재 조건을 만족시키지만, 등속도 표적 모델에 대하여 시선각 변화율의 초기값이 매우 작은 경우에는 유도 초반에 그 조건을 만족시키지 못한다. 수정 적응 단속 기동은 시선각 변화율 초기값이 매우 작은 경우에 대하여 유도 초반에 시선각 변화율이 커지는 방향으로 유도 명령을 생성함으로써 가관측성 존재 조건을 만족시키도록 설계된다. 설계된 수정 적응 단속 기동 기법의 가관측성 향상 성능은 시뮬레이션을 통하여 살펴본다. This paper deals with the observability enhancement of target state estimation system with bearing-only measurement. Adaptive Intermittent Maneuver (AIM) maintains the magnitude of line-of-sight(LOS) angle rate to be larger than certain threshold value to satisfy the observability conditions. However, in the case that the initial magnitude of LOS angle rate is smaller than the threshold value and the target dynamics is modeled as constant velocity model, the observability conditions are not satisfied at the early stage. Modified Adaptive Intermittent Maneuver (MAIM) is designed to enhance the observability for small initial LOS angle rate case by exerting guidance command to enlarge the magnitude of LOS angle rate at the early stage. Simulations are conducted to analyze the performance of MAIM.

선박의 부가저항 평가를 위한 소프트 계류 모형시험 기법 연구

서민국,박인보,박동민,황승현 대한조선학회 2023 大韓造船學會 論文集 Vol.60 No.5

In this study, a model test was conducted using the soft-mooring technique to evaluate the added resistance of the ship in waves. The study also examined the specific factors that should be considered during the soft-mooring test. The main purpose of soft-mooring is to prevent drifting caused by waves by providing horizontal restoring forces. However, it can also create undesired restoring forces in the vertical direction. Therefore, we examined the restoring force of the ship's 6-DOF motion based on the arrangement of the soft-mooring and the height of the mooring connection point. We also checked the corresponding resonance period and drift distance. The soft-mooring test was conducted twice, once with self-propulsion and once without self-propulsion, allowing us to review the advantages and disadvantages of each test technique. The main parameters measured in these model tests were 6DOF motion and added resistance on the ship. We compared these measurements obtained from two different techniques (with and without self-propulsion). Additionally, we also compared the measurements based on the types of measuring sensors used (2D load cells on FP, AP, and 1D load cells on each mooring line) as well as the height of the mooring connection point.

약한 비선형성을 고려한 선박의 선형에 따른 부가저항 비교분석

서민국,김경환,박동민,김용환 한국해양환경·에너지학회 2012 한국해양환경공학회 학술대회논문집 Vol.2012 No.5

Recently, the design of commercial ships with less green-house gas is one of great interests in naval architecture fields. Ship designers are asked to find optimum hull forms with minimum resistance in ocean waves. The accurate computation of added resistance, therefore, is getting more important for the prediction of power increase in random ocean waves. This study focuses on the numerical computation of added resistance on ships with Ax-bow shapes which are designed to reduce added resistance. To this end, the time-domain Rankine panel methods based on weakly-nonlinear and weakㅡscatterer approaches are applied, which can reflect the influence of aboveㅡstill water bow shape. As computational models, KCS and KVLCC2 hull forms are considered. Each ship is combined with the three types of Ax-bow shape, and computational results are compared each other.

약한 비선형성을 고려한 선박의 선형에 따른 부가저항 비교분석

서민국,김경환,박동민,김용환 대한조선학회 2012 대한조선학회 학술대회자료집 Vol.2012 No.5

Recently, the design of commercial ships with less green-house gas is one of great interests in naval architecture fields. Ship designers are asked to find optimum hull forms with minimum resistance in ocean waves. The accurate computation of added resistance, therefore, is getting more important for the prediction of power increase in random ocean waves. This study focuses on the numerical computation of added resistance on ships with Ax-bow shapes which are designed to reduce added resistance. To this end, the time-domain Rankine panel methods based on weakly-nonlinear and weak-scatterer approaches are applied, which can reflect the influence of above-still-water bow shape. As computational models, KCS and KVLCC2 hull forms are considered. Each ship is combined with the three types of Ax-bow shape, and computational results are compared each other.