• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.6
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• pp.101-106
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• 2002

In a bank-to-turn(BTT) missile, if a 2-gimbaled seeker was stabilized using a 2-axis rate gyro mounted along its primary axis, the change of line of sight(LOS) measured by the seeker would be induced by rolling effects due to bank-to-turn(BTT) steering as well as an actual change. It is observed that the body-coupled effects in a homing loop of BTT missile are mainly concerned with the spurious target maneuver and the coupling due to the rate gyro misalignments. In this paper, we formulate a simple linear BTT homing loop model with seeker model including each body-coupling. With the model, we analyze the effects of the couplings on the homing loop stability, and propose a direct linear compensator for the coupling to recover the stability.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.4
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• pp.316-323
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• 2016

A UAV(Unmanned Aerial Vehicle) flies along pre-programed navigation points(in-flight, take-off, or landing) automatically without pilot input. Even though UAVs fly differently from general piloted aircraft as the pilot controls the aircraft from a ground station through means of a data-link system. Occasionally, the data-link connection can be lost for any number of reasons, in which case, the FLCC(Flight control Computer) must automatically switch to autopilot to continue flying. Hence, the FLCC is a flight-critical component that must be throughly tested and validated. This paper discusses the development of a HILS(Hardware in the Loop Simulation) test environment designed to simulate real flight conditions to verify the FLCC satisfies flying quality requirements and maintains robustness despite any potential malfunctions or emergency situations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.116-123
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• 2003

In this paper, interleaved boost converter is applied as a pre-regulator in switched mode power supply. The pre-regulator plays a role to improve power factor. Interleaved Boost Power Factor Corrector(IBPFC) can reduce input current ripple as a single voltage control loop only without inner current loop, because input current is divided each 50% by two switching devices. Each converter cell is also operated in discontinuous current mode and inductor current of each converter is discontinuous. Total input current which is composed by each converter cell is continuous current. Thus, IBPFC is able to improve input current ripple. IBPFC operating in discontinuous current mode can be classified as six modes from switching state and be carried out state space averaging small signal modeling. A control transfer function is obtained according to the modeling. Single voltage control loop is also constructed by the control transfer function. From experimental result, improvement of power factor and input current ripple are verified.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.4
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• pp.283-288
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• 2019

In this paper, there is summarized the validation of ground test results through the telemetry acquired during on-orbit initial activation on solar-array drive assembly(SDA) of GK2A launched at Dec-5, 2018. Especially, the decision logic of SDA initial position and the compensation logic are validated and confirmed. The SDA initial position is needed when GK2A enter to geostationary orbit from transfer orbit and the compensation logic is for the accumulated position error due to the open-loop control. Up to now, it is normal operating. Also the periodic offset between the geostationary orbit and Sun position is found that it is not checked on design phase, and then the proper threshold value is applied.

• Geophysics and Geophysical Exploration
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• v.10 no.4
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• pp.308-313
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• 2007

The small-loop electromagnetic technique has been used successfully for many geophysical qualitative investigations, particularly for shallow engineering and environmental surveys. Recently, various geophysical imaging methods based on numerical modeling and inversion have been tried in order to get more quantitative subsurface structure. However, conventional 2.5D small loop EM modeling takes a lot of time because responses should be calculated for several wave numbers and transformed into space domain. In this study, we developed a 2.5D HCP small loop EM modeling algorithm using extended Born approximation, which does not require transformation. Also, we checked its validity by comparison with other numerical results.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.1
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• pp.68-77
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• 2018

In order to analyze the overall characteristics of the lunar orbiter, the Variable Coast method, which can be launched everyday, is applied to the 3.5 phasing loop transfer trajectory. The mission scenario for the entire process from launching to entering the lunar orbit is set up and performed simulation by selecting the launch pad and launch vehicle. In particular, the SEM(Satellite-Earth-Moon) angle defined in Earth-Moon rotating frame is an important constraint to comprehensively evaluate the 3.5 phasing loop transfer trajectory. The simulation using SEM angle is analyzed from various viewpoints such as launch epoch, coast duration, perigee altitude and ${\Delta}V$ not only trans-lunar trajectory but lunar orbit insertions and the optimum SEM angle is suggested in this study. It is expected that this results will be helpful to evaluate the characteristics of the 3.5 phasing loop transfer trajectory according to the launch vehicle selection by comparison with Fixed Coast analysis results in the future.

• The Bulletin of The Korean Astronomical Society
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• v.43 no.1
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• pp.70.3-70.3
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• 2018

외계행성 탐색시스템의 망원경-카메라 제어 시스템 및 소프트웨어 구성과 관측 유틸리티에 대해 소개한다. 망원경 제어 소프트웨어는 천문 위치보정, 포인팅, 돔 회전 등을 담당하는 PC-TCS 프로그램, 망원경 적경-적위 축 서보 제어를 담당하는 full-closed loop PID 컨트롤 프로그램, 포커서, 필터박스, 돔 셔터, 주경냉각, 온도 모니터 등의 보조 시스템을 제어하는 AUX controls 프로그램으로 구성된다. 카메라 제어 소프트웨어는 모자이크로 구성된 여러 CCD를 각각 독립적으로 제어하는 IC(Instrument Control) 패키지와 이들을 총괄 제어하는 ICS(IC Science) 패키지로 구성되며 망원경과 카메라 소프트웨어의 인터페이스 역할을 하는 TCS Agent 프로그램이 포함된다. 관측 진행을 돕는 유틸리티로서 관측제어 명령어 입력 및 관측 스크립트 구동 기능을 제공하는 OBS Agent 프로그램과 가이드 CCD를 이용한 시상 모니터링 및 자동초점조정 프로그램을 개발하여 활용하고 있다. 각 소프트웨어는 UDP, TCP/IP, RS-232, Redis server 등 다양한 인터페이스를 통하여 서로 통신하며, CCD 영상 자료 전달을 위해 RAM(Random Access Memory) 디스크와 Network File System(NSF)을 이용하고 있다.

• Journal of Trauma and Injury
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• v.30 no.4
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• pp.216-219
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• 2017

Laparoscopy has been one of the most effective modalities in various surgical situations, although its use in trauma patients has some limitations. The benefits of laparoscopy include cost-effectiveness, shorter length of hospital stay, and less postoperative pain. This report describes diagnostic laparoscopy and laparoscopic diverting sigmoid loop colostomy in penetrating extraperitoneal rectal injury. A 41-year-old male presented with perineal pain following penetrating trauma caused by a tree limb. Computed tomography showed air density in the perirectal space and retroperitoneum. As his vital signs were stable, we performed diagnostic laparoscopy and confirmed no intraperitoneal perforation. Therefore, laparoscopic diverting sigmoid loop colostomy was performed. He was discharged without any complications despite underlying hepatitis C-related cirrhosis. Colostomy closure was performed 3 months later.

• Journal of Power Electronics
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• v.11 no.4
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• pp.471-478
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• 2011

This paper addresses the establishment of a kVA-range plug-in hybrid electrical vehicle (PHEV) integration test platform and associated issues. Advancements in battery and power electronic technology, hybrid vehicles are becoming increasingly dependent on the electrical energy provided by the batteries. Minimal or no support by the internal combustion engine may result in the vehicle being occasionally unable to recharge the batteries during highly dynamic driving that occurs in urban areas. The inability to sustain its own energy source creates a situation where the vehicle must connect to the electrical grid in order to recharge its batteries. The effects of a large penetration of electric vehicles connected into the grid are still relatively unknown. This paper presents a novel methodology that will be utilized to study the effects of PHEV charging at the sub-transmission level. The proposed test platform utilizes the power hardware-in-the-loop (PHIL) concept in conjunction with high-fidelity PHEV energy system simulation models. The battery, in particular, is simulated utilizing a real-time digital simulator ($RTDS^{TM}$) which generates appropriate control commands to a power electronics-based voltage amplifier that interfaces via a LC-LC-type filter to a power grid. In addition, the PHEV impact is evaluated via another power electronic converter controlled through $dSPACE^{TM}$, a rapid control systems prototyping software.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.12
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• pp.59-66
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• 2010

We developed a model-based controller for 6-DOF micropositioning of a precision stage using $H_{\infty}$ norm, For the design, a state-space system of the mathematical model of the stage is derived In developing the controller, weighting functions are effectively designed in consideration of upper bounds of the sensitivity of the control loop and control input. Step responses in open and closed loop control are provided to verify the micropositioning performance of the stage. By applying the developed controller we prove that the inverse of the weighting function forms the upper bound of the control loop. It is also found that the controller makes the same sensitivity shape with all the DOFs due to the use of $H_{\infty}$ norm. The developed controller is expected to be applied successfully for industrial use.