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김성근,김인래,김승균,석진영,Kim, Sungkeun,Kim, Inrae,Kim, Seungkeun,Suk, Jinyoung 한국항행학회 2017 韓國航行學會論文誌 Vol.21 No.5
This paper presents dynamic modelling and simulation study on attitude/altitude control of an insect-mimicking flapping micro aerial vehicle during hovering. Mathematical modelling consists of three parts: simplified flapping kinematics, flapping-wing aerodynamics, and six degree of freedom dynamics. Attitude stabilization is accomplished through linear quadratic regulator based on the linearized model of the time-varying nonlinear system, and altitude control is designed in the outer loop using PID control. The performance of the proposed controller is verified through numerical simulation where attitude stabilization and altitude control is done for hovering. In addition, it is confirmed that the attitude channel by periodic control is marginally stable against periodic pitching moment caused by flapping. 본 연구에서는 곤충모방 날갯짓 비행체의 모델링과 제자리비행을 위한 자세제어 및 고도제어기를 설계하여 동역학 모델을 이용한 시뮬레이션을 수행하고 그 결과를 분석하였다. 곤충모방 날갯짓 비행체의 간략화한 날갯짓 운동, 날갯짓의 병진운동 및 회전운동에 대한 공력, 동체 동역학에 대해 수치모델링을 수행하였다. 제자리비행 자세제어를 위해 날갯짓 비행체가 가지는 시변 비선형 시스템을 선형화하여 설계한 LQR(Linear Quadratic Regulator) 제어기법을 통하여 자세안정화를 적용하였으며 PID 제어기법을 통해 고도제어를 수행하였다. 수치 시뮬레이션을 통해 설계된 모델과 제어기의 성능을 확인하였으며 제자리비행을 위한 자세안정화 및 고도 제어가 안정적으로 수행되는 것을 확인하였다. 또한 날갯짓에 의해 발생하는 주기적인 피칭 모멘트를 주기적인 제어입력을 통해 임계 안정하도록 자세 안정화를 수행하는 것을 확인 하였다.
회전익 무인항공기의 LQTI 제어기와 비행특성 평가 연구
김성근(Sungkeun Kim),김기준(Kijoon Kim),라충길(Chunggil Ra),김승균(Seungkeun Kim),석진영(Jinyoung Suk),문정호(Jungho Moon) 한국항공우주학회 2016 한국항공우주학회 학술발표회 논문집 Vol.2016 No.4
본 논문에서는 복잡한 비선형성의 회전익 무인항공기의 자세제어를 위해 비교적 간단한 구조의 Linear Quadratic Regulator을 기반으로 한 Linear Quadratic Tracker with Integrator를 통해 효과적인 자세제어기를 구성하였다. 이때 설계된 제어기를 이용한 회전익 무인항공기의 비행특성(Handling Qualities)을 ADS-33E-PRF를 활용하여 비행특성 평가 시뮬레이션을 수행하였다. 비행 특성평가는 공중 제자리 비행 및 저속비행 상태에서 조종입력에 대한 응답확인으로 frequency sweep 입력에 대한 미소 진폭 자세변화의 단주기 응답에 대한 평가를 진행하였다. 이를 통해 비행 특성을 파악하고 Linear Quadratic Tracker with Integrator의 Q, R 선정에 대한 영향을 분석하였다. This paper designs linear quadratic tracker with integrator of a relatively simple structure for attitude control of a complex nonlinear unmanned helicopter. In this case, handling qualities of a helicopter is investigated through simulations with controller design based on ADS-33E-PRF which uses a short term response regarding a frequency sweep input at hover and low speed flight. This helps understand the handling qualities of the unmanned helicopter and analyze the effect on Q and R matrices of the linear quadratic tracker with integrator.
수술 후 조기에 재발하여 경동맥화학색전술로 완치된 간세포암종 증례
김희언 ( Hee Yeon Kim ),김창욱 ( Chang Wook Kim ),김성근 ( Sungkeun Kim ),이수림 ( Soo Lim Lee ),구영미 ( Young Mi Ku ),원유동 ( Yoo Dong Won ) 대한간암학회 2018 대한간암학회지 Vol.18 No.2
Although surgical resection is a curative treatment option for solitary hepatocellular carcinoma, high recurrence rate contributes to dismal long-term prognosis after curative resection. Early recurrence within 2 years after surgery is associated with intrahepatic metastasis of primary tumor. Liver regeneration after hepatic resection can accelerate tumorigenesis in remnant liver. Treatment strategies for intrahepatic recurrence after curative resection include salvage transplantation, repeated resection, local ablation, and transarterial chemoembolization (TACE). Here, we report a 51-year-old male who was presented with a single large tumor located at segment 4. The patient was initially treated with surgical resection, but intrahepatic recurrence occurred only 4 months after surgery. He achieved complete remission with repeated TACE and has survived without recurrence for 4 years so far. (J Liver Cancer 2018;18:162-167)
LQTI를 이용한 회전익 무인항공기 종방향 조종성 평가를 위한 제어법칙 설계 및 조종성 평가
이창민(Changmin Lee),김성근(Sungkeun Kim),조승환(Seunghwan Jo),라충길(Chunggil Ra),김기준(Ki-joon Kim),석진영(Jinyoung Suk),김승균(Seungkeun Kim) 한국항공우주학회 2017 韓國航空宇宙學會誌 Vol.45 No.5
본 논문에서는 회전익 무인항공기의 조종성 평가를 수행하기 위한 가상모의시험용 프로그램을 MATLAB GUIDE(Graphic User Interface Development Environment)를 활용하여 개발하였다. ADS-33E에 기반을 둔 조종성 평가 프로그램은 비행제어시스템을 개발하고 조종성을 평가하는 데에 있어 시간과 비용을 경감시킬 수 있을 것으로 사료된다. 또한, Linear Quadratic Regulator(LQR)기반의 Linear Quadratic Tracker with Integrator(LQTI) 자세제어기를 BO-105C 회전익 항공기에 적용하여 조종성을 평가하고 Q와 R의 가중치에 따른 조종성에 대한 경향을 분석하였다. A virtual simulation test program to carry out the handling qualities of unmanned Rotorcraft has developed by using the MATLAB GUIDE(Graphic User Interface Development Environment). The handling quality evaluation program based on ADS-33E contributes to design the flight control system and to evaluate handling qualities. In addition, Linear Quadratic Tracker with Integrator(LQTI) attitude controller based on Linear Quadratic Regulator(LQR) for to rotorcraft BO-105C and the effects of the handling qualities is analyzed change to weight matrices of the Q and R.
황선필 ( Sunpil Hwang ),김성근 ( Sungkeun Kim ) 한국유통경영학회(구 한국유통정보학회) 2021 유통경영학회지 Vol.24 No.3
Purpose: This study examines the relationship between profit-generating capabilities and dividend propensity. For this purpose, DuPont Analysis is used. Research design, data, and methodology: Accordingly, DuPont Analysis names these two parts (ATO and PM) as profit-generating capabilities and verifies that the firm’s relationship to dividend payout is different, in addition to the ROA, which means the entity’s simple level of profit. Furthermore, based on a study by Jansen et al. (2012), the study classifies suspected earnings management firms (DPEQ) using ATO and PM and validates their relevance to dividend payout. To confirm the above, the results of the analysis using 12,207 data from 2010 to 2019 are summarized as follows. Results: First, it has been shown that both ATO and PM have a significant amount of relevance to the next dividend payout even after controlling certain variables. This means that both asset-efficient and cost-effective entities have a high dividend payout. Second, it was observed that the DPEQ measured as ATO and PM had a significant amount of relevance to the next period dividend payout. Specifically, the lower the asset efficiency and the higher the cost efficiency, the higher the next dividend payout. Further analysis showed that the results of this study differed according to the differences in listed markets (KOSPI vs. KOSDAQ) and the size of foreign investors’ ownerships, and that the main analysis was more apparent in the KOSPI market and the high foreign investors’ ownerships was not significant in ATO. Implications: Based on the results of the above research, DuPont Analysis may be useful in academia and practice as capital market investors may use it as a substitute method for identifying earnings management.
태양돛 시험용 큐브위성 CNUSAIL-1의 임무 및 시스템 개념설계
구소연(Soyeon Koo),김경훈(Gyeonghun Kim),유연아(Yeona Yoo),송수아(Sua Song),김성근(Sungkeun Kim),오복영(Bockyoung Oh),우범기(Beomki Woo),한창구(Chang-Gu Han),김승균(Seungkeun Kim),석진영(Jinyoung Suk),한상혁(Sanghyuck Han),최기혁(Gi-Hyu 한국항공우주학회 2014 韓國航空宇宙學會誌 Vol.42 No.7
CNUSAIL-1은 태양돛을 탑재한 3U크기의 큐브위성이다. 주 임무는 저궤도에서 태양돛을 전개하는 것이며, 추가적으로 태양돛 전개와 태양돛 운용에 따른 위성의 자세/궤도변화를 확인하는 임무를 수행한다. 이를 위해, 위성의 각 시스템은 위성의 동적 데이터와 태양돛 작동 사진을 수집하고 지상국으로 전송한다. 본 논문에서는 이와 같은 임무를 수행하는 CNUSAIL-1의 태양돛 임무를 소개하고 시스템 개념설계 결과를 나타낸다. 탑재체인 태양돛의 구동 및 운용 원리를 구현하고, 버스시스템을 자세제어계, 통신계, 전력계, 명령 및 데이터 처리계, 구조 및 열 제어계로 나누어 개념 설계를 수행한다. The CNUSAIL-1 project aims to develop and operate a 3U-sized cube satellite with solar sail mechanism. The primary mission is to successfully deploy the solar sail in a low earth orbit, and the secondary mission is to collect the scientific data for the effect of the solar sail deployment and operation on orbit maneuver and attitude change of the cube satellite. For this, the bus system will collect and transmit the dynamic data of the satellite and the visual images of the solar sail operation. This paper describes solar sail mission and conceptual design of CNUSAIL-1. The actuation/operation of the solar sail and the bus system are preliminarily designed in terms of attitude control system, communication system, electrical power system, command and data handling system, structure and thermal control system is designed.
유기물 제어를 통해 분리막의 fouling을 저감시키는 MBR 공정개발
이한슬 ( Hanseul Lee ),김진수 ( Jinsu Kim ),심재훈 ( Jaehoon Shim ),강민구 ( Minkoo Kang ),김성근 ( Sungkeun Kim ),이상일 ( Sangill Lee ) 한국수처리학회 2015 한국수처리학회지 Vol.23 No.4
The process which apply the Membrane bioreactors(MBRs) provide many advantages over conventional treatment so that process with MBR is being applied for industrial wastewater treatment. However, membrane fouling is main obstacle for application of MBRs because it reduces washing-cycle and productivity. The bio- fouling caused by EPS, NOM, pore size, HRT, etc. In this study, MLE(modified Ludzack-Ettinger) process with adding an aerobic reactor(M2) process operated to control bio-fouling feasibly in MBRs. As install an oxic unit in MLE, COD removal efficiency was more excellent than existing MLE process. Also, the total amount of extracellular polymeric substance(EPS) extracted from M2 reactor was lower concentration than M1. Controlling the EPS, M2 process washing cycle was longer than M1 about a week. It showed that, bio-fouling is influenced by the concentration of EPS and adding an oxic unit to MLE is very effective to control the bio-fouling.
공항공사와 항공사 아웃소싱 직원의 근무환경과 직무만족, 조직 유효성 간의 관계 연구
권순호 ( Soonhho Kwon ),배은주 ( Eunjoo Bae ),김성근 ( Sungkeun Kim ) 관광경영학회 2018 관광경영연구 Vol.82 No.-
The main purpose is the effectively improving the working conditions of the two groups and keeping a high level of service quality and aims to contribute to raise the world's most competitive airport services. First, recognition on work environment of Incheon International Airport and the airline outsourcing staffs shows that there is a difference. In particular, external working environment related with salaries and benefits, environment-related work conditions and the social working environment related with staff's cooperation, atmosphere at work, etc. has shown a difference. Second, between airlines outsourcing staffs on working environment and organizational citizenship behavior, the relationship of external working environment related with salary, benefits, good working environment and organizational citizenship behavior affects negative(-). Third, the manager of airport cooperation and airline has to make on effort for improvement with constant attention due to the effects of the perception of working environment on job satisfaction and organizational effectiveness is very large impact. Fourth, the difference analysis of the demographic characteristics are more interested and sensitive to working environment, job satisfaction and organizational commitment on less than one year of service staff and spent more than 4 years or 5 years of service staffs. To maintain service competitiveness and quality, it absolutely needs to special care and improvement in order to meet the staffs' interests related to working environment, job satisfaction and organizational commitment working for less than one year staff and over 5 years of service staffs considering change of occupation.