• 한국군사과학기술학회지
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• 제20권2호
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• pp.246-254
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• 2017

In this paper, cooling characteristics of seeker windows were examined using the Sinda-Fluint software. Various cooling methods were considered to satisfy the limit temperature of the cooled seeker window which would be exposed to excessive aerodynamic heating conditions by varying coolant type and mass flow rate of coolant. Due to the enhanced heat transfer between the coolant and the seeker window, internally cooled seeker window which uses liquid coolant showed lowered temperature distribution in the window compared to internally cooled seeker window which uses gas coolant. External film cooled seeker window also showed good cooling characteristics because it reduces the convective heat flux to the seeker window fundamentally. It was also confirmed that the temperature and the temperature gradient of seeker windows were significantly reduced for the cases which use external film cooling additionally to the gas and liquid cooled seeker window.

• International Journal of Aeronautical and Space Sciences
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• 제9권2호
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• pp.87-97
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• 2008

Modem anti-ship missiles employ complex and sophisticated guidance laws to hit the target and enhance their survivability by executing additional maneuvers. However, such maneuvers may cause the target to move out of the missile seeker's Field-Of-View (FOV). Maintaining seeker lock-on during an engagement is a critical factor for missile guidance. In this paper, a guidance law switching logic that maintains seeker lock-on and a simple guidance law that keeps the target look angle of the seeker constant is proposed. The proposed method can be used for the terminal homing phase, and can be switched from any kind of guidance laws if a proper switching condition is satisfied. The minimum and maximum flight time calculation method in consideration of the missile maneuver limit and the FOV of the seeker is also provided.

• 제어로봇시스템학회논문지
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• 제19권3호
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• pp.275-280
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• 2013

Conventional proportional navigation guidance law is not adequate for missiles with a strapdown seeker, because the strapdown seeker cannot measure line-of-sight rate directly. This paper suggests a guidance loop design method, in which the look angle, measured by the strapdown seeker directly, is controlled to deliver a missile to a target. Basically, the look angle control loop is regarded as an attitude control loop. By using the proposed method, it is possible to shape the midcourse trajectory by choosing the reference look angle properly. The look angle control loop can robustly maintain target lock-on against disturbances because the target is always captured in the field of view of the seeker. The performance of the proposed method is verified via 6-DOF simulations of a true short range tactical missile model.

• 전자공학회논문지S
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• 제35S권5호
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• pp.35-41
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• 1998

This paper presents a decoupling controller of the missile seeker scan loop with a spin-stabilized platform. A precise seeker motion with respect to the scan command is essential for the higher acquisition probability of the target. As the seeker scan loop is a deeply cross-coupled two input two output system, an accurate pointing or scanning for each axis to the target is very difficult, even though provided with the help of a high performance controller. When a decoupling control is applied to the seeker scan loop, the cross-coupling between two axes can be reduced to a remarkable amount. As a low order of controller is required for the real time operation, a PI controller with decoupling filter is suggested and compared with other controllers. A linearized dynamic model of seeker scan loop is used and validated through the comparison of experimental results of step responses.

• 한국항공우주학회지
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• 제38권3호
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• pp.221-227
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• 2010

일반적인 전술유도탄에서 표적획득 센서로 사용되는 김발형 탐색기(Gimballed Seeker) 는 탐색기의 표적획득부가 유도탄의 동체운동과는 독립적으로 관성좌표계 상에서 표적을 지향하게 하여 비례항법 유도명령 생성에 필요한 유도탄/표적간의 시선 각속도 정보를 직접 제공한다. 반면 최근에는 탐색기 전체가 유도탄 동체에 고정됨으로써 정비보수 용이, 고장수리 감소, 단가감소 측면 등에서 유리한 동체고정 탐색기(Strapdown Seeker)에 대한 연구가 부분적으로 수행되고 있다. 그런데 동체고정 탐색기에서는 비례항법에 필요한 시선각속도가 직접주어지지 않고 탐색기 영상 평면에 맺힌 표적영상으로부터 유도명령생성에 필요한 정보를 추출하여야 한다. 본 연구에서는 먼저 스트랩다운 탐색기로부터 주어지는 표적정보를 바탕으로 언센티드 칼만필터(Unscented Kalman Filter, UKF)를 적용하여 유도탄과 표적간의 상대운동을 추정한다. 추정된 상대운동 정보를 이용하여 유도명령을 생성하고 유도탄과 표적간의 조우운동을 시뮬레이션을 통하여 검증하였다.

• Journal of Electrical Engineering and Technology
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• 제8권1호
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• pp.190-196
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• 2013

This paper proposes a new guidance law, which considers the Field of View (FOV) of the seeker when a missile has a strapdown seeker mounted instead of a gimbal seeker. When a strapdown seeker, which has a narrow FOV, is used for tracking a target, the FOV of the seeker is an important consideration for guidance performance metrics such as miss distance. We propose a new guidance law called hybrid guidance (HG) to address the shortcomings of conventional guidance laws such as proportional navigation guidance (PNG), which cannot maintain lock-on conditions against high speed targets due to the narrow FOV of the strapdown seeker. The aim of the HG law is to null miss distance and to maintain the look angle within the FOV of the strapdown seeker. In order to achieve this goal, we combine two guidance laws in the HG law. One is a PNG law to null the LOS rate, and the other is a sliding mode guidance (SMG) law derived to keep the look angle within the FOV by employing a Lyapunov-like function with a sliding mode control methodology. We also propose a method to switch these two guidance laws at certain look angles for better guidance performance.

• 한국식품영양학회지
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• 제29권2호
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• pp.267-274
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• 2016

Increasing sugar intake of population has become a nutritional issue in Korea. Sweet taste perception may be related to behaviors such as eating sweet food including high sugars and total sugar intake. This study aimed to evaluate objective and subjective sweet taste perception and the association among objective sweet taste perception, dietary behaviors related to eating sweet snack food including high sugar, and total sugar intake from the snacks. Participants were 261 healthy female college students (mean age: $21.0{\pm}1.6years$), who were divided into three subgroups based on oral sweet taste evaluation using a sweet taste assessment tool provided by Ministry of Food and Drug Safety: sweet-seeker group (n=139), medium sweet-seeker group (n=54), and unsweet-seeker group (n=68). There was no significant difference in weight and body mass index (BMI) among the three groups; however, the sweet-seeker group had significantly higher sweet taste preference than that of the other groups. Though more people in the sweet-seeker group thought they tended to eat sweet foods than the medium sweet-seeker and unsweet-seeker groups, over half of the sweet-seekers did not think they tended to eat sweet foods. The sweet-seeker group was more likely to eat sweet snacks such as breads, chocolate products, sugar-sweetened milk, and so on than the unsweet-seeker group. Total sugar intake from the selected sweet snacks was 44.4 g for the sweet-seeker group, 34.4 g for the medium sweet-seeker group, and 28.0 g for the unsweet-seeker group with a significant difference. These results indicated the absence of relationship between objective sweet taste perception and the obesity index; however, significant associations were detected among objective sweet taste perception, eating sweet snacks and total sugar intake from the snacks. We also found high disagreement between objective and subjective sweet taste perception of the subjects. The present study provided the novel insight that measuring objective sweet taste perception may be useful for assessing the risk of high sugar consumption and undesirable dietary behaviors.

• 한국군사과학기술학회지
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• 제13권2호
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• pp.304-312
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• 2010

The function of IRCM(Infrared Countermeasures) jamming is to cause the missile to miss its intended target by disturbing the seeker tracking process. This paper analyzes the jamming effect of IRCM jamming for a stationary reticle seeker. The phase error containing the azimuth angle information of target is analyzed for the intensity, frequency and duty ratio variation of the jammer pulse signal. We confirmed that the more the jammer frequency is similar to the spinning frequency of the stationary seeker, the more jamming effect is high.

• 한국군사과학기술학회지
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• 제7권3호
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• pp.30-37
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• 2004

For a proper operation of portable air defense IR terminal homing missile to the rapid intruding target, the boresight of an IR seeker of the missile should be accurately aligned with the gunner's aiming sight. Before a gunner fires the missile, he tries to keep the target within the circle of ASU ensuring the seeker to lock on the target correctly. In this paper, using an electrical seeker caging loop and IR detector signal characteristics, a precise aligning method between the seeker boresight and the LOS(Line of Sight) of ASU(Aiming Sight Unit) was studied. Although every seeker has slightly different SLA (Signal of Look Angle) output, we can get negligible alignment error through a fine tuning method of electrical caging signal. This alignment procedure was also adopted in K-PSAM system.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.1536-1541
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• 2003

The model of azimuth driving servo system with a flexible antenna in a microwave seeker has been derived in this paper. The validity of the model is verified by comparing the result of the model with that of experiment. It is found that one should consider an antenna as a flexible body in case of modeling the dynamics of the microwave seeker. It is also known that the effect of reducing backlash magnitude for extending the bandwidth in the system with a flexible antenna is smaller than that in the system with a stiff antenna. It is thought that the model-based design optimization of the microwave seeker will become possible by virtue of the derived model, when a weight reduction and a bandwidth extension are required.