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탄도미사일 하층 방어 수행을 위한 발사대 배치 효과도 분석
권혁훈,이범석,김윤환,최관범,Kwon, Hyuck-Hoon,Lee, Bum-Seok,Kim, Yoon-Hwan,Choi, Kwan-Bum 한국군사과학기술학회 2013 한국군사과학기술학회지 Vol.16 No.5
For a lower tier defense, the distance between a launcher and an engagement control station is quite important to estimate the proper defense area and to effectively arrange missile launchers. In this paper, we have analyzed an effectiveness of anti-ballistic missile launcher arrangement for the lower tier defense against the ballistic missile. The operation concept, specific configuration and aerodynamic characteristics of the ballistic missile such as SCUD-B/C, Nodong are considered in order to develop a realistic engagement simulation. The diverse engagement results through numerical simulations are provided to conduct the effectiveness analysis of anti-ballistic missiles.
IMU 탑재 위치 및 유도탄 무게 중심 변화율에 따른 Three-Loop 조종 알고리듬 안정성 분석
권혁훈(Hyuck-Hoon Kwon),김윤환(Yoon-Hwan Kim),박봉균(Bong-Gyun Park) 한국항공우주학회 2016 韓國航空宇宙學會誌 Vol.44 No.6
유도탄 가속도 제어에 일반적으로 널리 사용되는 Three-Loop 조종 알고리듬은 유도탄에 탑재된 IMU에서 제공되는 가속도 및 각속도 정보를 사용한다. Three-Loop 조종 알고리듬에 입력되는 가속도 명령은 유도탄의 무게 중심에서 발생하는 가속도로 주어지기 때문에 IMU에서 획득되는 정보 역시 무게 중심에서의 값으로 주어져야 한다. 하지만, 유도탄의 내부 배치 설계나 추진기관의 연소 등에 의하여 IMU가 유도탄의 무게 중심이 아닌 임의의 위치에 배치되는 경우가 대부분이다. 본 논문에서는 Three-Loop 조종 알고리듬에서 피드백되는 가속도 정보가 유도탄의 무게 중심이 아닌 임의의 위치에서 획득된 값일 경우, IMU 탑재 위치 및 유도탄 무게 중심 변화율이 유도탄 조종 알고리듬 안정성에 미치는 영향을 분석하였다. 일반적인 대전차 유도탄에 대하여 이득 및 위상 여유 분석을 수행하였다. Three-Loop autopilot is generally used for the acceleration control of guided missiles. Because the acceleration command to the three-loop autopilot is given as values at the center of gravity, feedback information of IMU should be obtained at the same position. However, the position of IMU might not be located at the center of gravity due to the sub-system assignment. This paper presents the stability analysis of three-loop autopilot with respect to the arbitrary position of IMU and variation rate of center of gravity. Gain and phase margins are calculated for several trim points for general anti-tank missiles.
컨벡스 프로그래밍을 이용한 추진-활공 유도탄의 중기궤적 최적화
권혁훈(Hyuck-Hoon Kwon),홍성민(Seong-Min Hong),김경훈(Gyeong-Hun Kim),김윤환(Yoon-Hwan Kim) 한국항공우주학회 2021 韓國航空宇宙學會誌 Vol.49 No.1
탐색기를 탑재한 유도탄의 중기궤적은 탐색기 시야(FOV : Field-Of-View) 내에서 표적을 탐지하며, 전환 시점에서의 기동성을 최대화하도록 설계하는 것이 요구된다. 유도탄의 비행궤적 최적화 문제는 여러 구속조건이 적용된 비선형 문제로 일반적인 해석해를 도출하기 어렵기 때문에 그 동안 다양한 계산적인 방법들이 제시되어 왔다. 본 논문에서는 추진-활공 유도탄의 중기궤적 최적화 문제를 컨벡스 최적화 기법인 2차 원뿔 프로그래밍을 이용하여 산출하였다. 먼저, 운동방정식의 상태변수를 최소화하기 위해서 제어변수 구속조건이 추가된 제어변수 추가 형태의 운동방정식을 구성하였다. 또한, 자유 종말시간 문제와 추진시간 문제를 대처하기 위하여 정규화된 시간 변수를 독립 변수로 설정하였다. 그리고, 운동방정식과 제어변수 구속조건을 컨벡스 형태로 변환하기 위하여 각각 부분 선형화와 무손실 컨벡스 변환을 적용하였다. 마지막으로, 본 논문에서 제시된 방안의 타당성을 확인하기 위하여 비선형 최적화 프로그래밍 결과와 비교하였다. Mid-course trajectory of the missiles equipped with seeker should be designed to detect target within FOV of seeker and to maximize the maneuverability at the point of transition to terminal guidance phase. Because the trajectory optimization problems are generally hard to obtain the analytic solutions due to its own nonlinearity with several constraints, the various numerical methods have been presented so far. In this paper, mid-course trajectory optimization problem for boost-glide missiles is calculated by using SOCP (Second-Order Cone Programming) which is one of convex optimization methods. At first, control variable augmentation scheme with a control constraint is suggested to reduce state variables of missile dynamics. And it is reformulated using a normalized time approach to cope with a free final time problem and boost time problem. Then, partial linearization and lossless convexification are used to convexify dynamic equation and control constraint, respectively. Finally, the results of the proposed method are compared with those of state-of-the-art nonlinear optimization method for verification.
순차 컨벡스 프로그래밍을 이용한 충돌각 제어 비행궤적 최적화
권혁훈(Hyuck-Hoon Kwon),신효섭(Hyo-Sub Shin),김윤환(Yoon-Hwan Kim),이동희(Dong-Hee Lee) 대한전기학회 2019 전기학회논문지 Vol.68 No.1
Due to the various engagement situations, it is very difficult to generate the optimal trajectory with several constraints. This paper investigates the sequential convex programming for the impact angle control with the additional constraint of altitude limit. Recently, the SOCP(Second-Order Cone Programming), which is one area of the convex optimization, is widely used to solve variable optimal problems because it is robust to initial values, and resolves problems quickly and reliably. The trajectory optimization problem is reconstructed as convex optimization problem using appropriate linearization and discretization. Finally, simulation results are compared with analytic result and nonlinear optimization result for verification.
한국인의 광노화 피부에서 592 nm 황색 파장 Light Emitting Diode의 치료 효과
문기랑 ( Ki Rang Moon ),권혁훈 ( Hyuck Hoon Kwon ),서대헌 ( Dae Hun Suh ),윤숙정 ( Sook Jung Yun ),이승철 ( Seung Chul Lee ),이지범 ( Jee Bum Lee ) 대한피부과학회 2015 대한피부과학회지 Vol.53 No.9
Background: As aging occurs, the skin develops more wrinkles and pigmentation, becomes drier, and loses its elasticity. In previous reports, light-emitting diode (LED) phototherapy was proven to stimulate collagen synthesis and accelerate fibroblast-myofibroblast transformation, which has a composite rejuvenation effect. Objective: To evaluate the effectiveness and safety of LED phototherapy with 592 nm yellow light for photoaged skin. Methods: Forty patients with photoaged skin (Korean photographic scale; grade 4∼7) were enrolled and treated with an LED device producing 592±10 nm yellow light for 5 minutes twice a week for 4 weeks. The skin changes were assessed at 0, 2, 4, and 8 weeks by clinical photographs and the Cutometer® & Mexameter® (MPA 580, Courage+Khazaka Electronic GmbH, Koln, Germany). Measurements were made on the cheek, periorbital area, nasolabial fold, and glabella. Results: At the final visit at 8 weeks, the Cutometer® parameters R4 and R6 decreased significantly compared to before treatment, from 0.118 to 0.099 for the periorbital (p=0.017) and 0.517 to 0.425 for the nasolabial fold (p=0.003). The average melanin index decreased significantly, from 133.65 to 124.55 (p<0.005). Fine improvement of wrinkles was shown grossly by reviewing follow-up clinical photographs. No adverse reactions occurred. LED phototherapy with 592±10 nm wavelength can be effective and safe in the treatment of photoaged skin. Conclusion: The findings suggest the LED with 592 nm yellow light might be an adjuvant therapeutic tool for photoaged skin. (Korean J Dermatol 2015;53(9):677∼683)
시변 연속적 편향 비례항법 유도법칙을 이용한 이동표적의 충돌각 제어
박장성(Jang-Seong Park),권혁훈(Hyuck-Hoon Kwon),박상혁(Sang-Hyuck Park),김윤영(Yoon-Young Kim),박봉균(Bong-Gyun Park) 한국항공우주학회 2018 韓國航空宇宙學會誌 Vol.46 No.9
본 논문은 지대지 교전상황에서 유도탄 탐색기의 Field-of-View(FOV)와 가속도 제한을 고려하여 충돌각을 제어하는 시변 편향 비례항법 유도법칙(Time Varying Biased Proportional Navigation Guidance Law)을 제안하고 있다. 제안한 유도법칙은 FOV 제한을 고려하여 3단계로 구성이 되는데 각 단계에서 편향이 가속도에 직접적인 영향을 미치기 때문에 편향을 생성하는데 있어서 단계가 넘어갈 때 전 단계의 마지막 편향이 다음 단계의 시작 편향이 되도록 하였다. 또한, 교전 상황과 물리적 구속조건을 고려하여 충돌각 도달 여부를 판단하는 로직 또한 설명하고 있다. In this paper, we propose a time varying biased proportional navigation guidance law that controls the impact angle under Field-of-View(FOV) and the acceleration limit of the missile. The proposed law is composed of three stages in consideration of the FOV limitation. Since the bias directly affects the acceleration at each stage, the final bias value of the previous stage becomes the initial bias value of the next stage when the stage is switched. In addition, the impact angles were controlled by judging whether impact angles were reached in consideration of engagement conditions and physical constraints.
최재우 ( Jae Woo Choi ),권혁훈 ( Hyuck Hoon Kwon ),조성진 ( Seong Jin Jo ),서대헌 ( Dae Hun Suh ) 대한피부과학회 2012 大韓皮膚科學會誌 Vol.50 No.2
Extraskeletal Ewing`s sarcoma is an extremely rare malignant soft tissue tumor, which presents the exact same histopathologic features with Ewing`s sarcoma of bone. Tumor composed of small, blue, round cells with vesicular nuclei and scant cytoplasm is the characteristic histopathology of the disease. Extraskeletal Ewing`s sarcoma is known to occur usually in the deep soft tissues of the extremities. We report a case of 22-year-old boy with solitary extraskeletal Ewing`s sarcoma on his back without any evidence of bone involvement. The patient went through wide excision with meticulous lymph node dissection followed by chemotherapy. For the 15 months of follow up, there is not a sign of recurrence or metastasis observed. (Korean J Dermatol 2012;50(2):147~151)