• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2001.11a
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• pp.252-256
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• 2001

본 논문에서는 IMT-2000 기지국용 2단 저잡음 증폭기를 설계했다. 잡음지수 특성이 뛰어난 HP사의 PHEMT 소자인 ATF-35143을 사용하였고 능동소자의 바이어스는 $V_{ds}$ 가 3 v $I_{d}$을 30mA로 설정했다. 첫 단은 최소잡음 지수에 중점을 두고 설계했고 둘째 단은 이득에 초점을 맞추어 설계했다. 입출력 정재파 비를 줄이기 위해서 전체증폭기의 앞단과 뒷단에 삽입손실이 0.2dB인 X503 SMT 90도 하이브리드 커플러를 설치 했다. 제작을 위해 기판은 두께 0.76mm이고 비유전율 4.2의 FR-4를 사용했다. 설계된 저잡음 증폭기의 특성은 주파수대역 1.92GHz～1.98GHz에서 잡음지수 0.45dB, 입출력 정재파 비 1.2이하, 이득은 32dB이상의 특성을 보였다.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.826-827
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• 2015

본 논문은 비선형적인 파라미터 특성을 갖는 Switched Reluctance Motor(SRM)의 강인제어를 위한 보다 정확하고 안정적인 전류제어 방법에 대해 설명한다. 기존의 전류제어 방법에는 이득설정이 간편한 PI 제어기를 이용한 방법이 주로 사용되어왔다. 본 논문에서는 자기동조 퍼지 제어기를 이용한 방법과 Dead-Beat 제어기를 이용한 방법을 통하여 파라미터의 변화에도 안정적인 전류제어가 가능한 것을 보였고 PI 전류 제어기와 자기동조 퍼지 전류 제어기, 그리고 Dead-Beat 전류 제어기를 각각 적용한 전류제어 SRM 드라이브의 Matlab/Simulink 시뮬레이션 결과를 통하여 제어성능을 비교분석하였다.

• Journal of IKEEE
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• v.7 no.1 s.12
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• pp.43-55
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• 2003

A degenerated differential pair has been widely used as a standard topology for digitally programmable CMOS VGAs. A variable degeneration resistor has been implemented using a resistor string or R-2R ladder with MOSFET switches. However, in the VGAs using these conventional methods, low-voltage and high-speed operation is very hard to achieve due to the dc voltage drop over the degeneration resistor. To overcome the problem a new variable degeneration resistor is proposed where the dc voltage drop is almost removed. The proposed gain control scheme makes it easy to implement a low-voltage and high-speed VGA. This paper describes the problems existed in conventional methods, the principle and advantages of the proposed scheme, and their performance comparison in detail. A CMOS VGA cell is designed using the proposed degeneration resistor. The 3dB bandwidths are greater than 650㎒ and the gain errors are less than 0.3dB in a gain control range from -12dB to +12dB in 6dB steps. It consumes 3.1㎃ from a 2.5V supply voltage.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.6
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• pp.602-611
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• 2004

Servo system has commonly adapted PI controller with fixed gains, because of its simplicity and determinative relationship among the parameters. The fixed gains PI system may be applied well to some operation conditions, but not non-linearities, complex and time variant operation conditions. For solving these problems, another conventional method, 'variable gun schedule according to speed', is published. The value of gain is determined according to the absolute value of the mover real speed. In this paper, FSTPIC(Fuzzy Self-Tuning PI Controller) is proposed based on various experiences to rapidly reduce speed error and to secure a good speed response characteristics. The effectiveness of proposed algorithms is demonstrated by comparing to two conventional gain systems via 4-quadrant operation.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.6
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• pp.537-544
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• 2009

This paper concerns analysis technique on determining of attitude control gain in the low frequency region using stability area. The stability area is defined by the D-Decomposition method, which was designed by Neimark. In this paper, it is introduced D-Decomposition method from reference paper and design attitude control gain of generic launch vehicle during first stage flight phase. For selecting PD control gain, it is considered the system parameter uncertainty about whole first-stage flight phase, represented the stability area boundary on each case. After deciding the PD control gain using stability area method, it is applied to launch vehicle linear model, and checking the stability margin requirement, frequency response characteristics.

• Proceedings of the KAIS Fall Conference
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• 2010.11b
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• pp.665-668
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• 2010

본 연구는 건강신념모형의 주요 변수와 신종인플루엔자 예방행동과의 관계를 파악하여 고등학생의 신종인플루엔자 예방행동에 대한 교육적 지도방안과 신종인플루엔자 예방프로그램 개발의 기초 자료를 제공하고자 시도되었다. 자료는 2009년 11월 1일에서 11월 24일까지 일부 광역시에 위치한 고등학교 4개교를 무작위 추출하여 1, 2학년 학생 총 683명을 대상으로 구조화된 설문지를 이용하여 조사하였다. 본 연구에서 심각성은 16점 만점에 평균점수 12.15(${\pm}$2.56), 감수성은 12점 만점에 평균점수9.34(${\pm}$1.90), 이득은 12점 만점에 평균점수 8.33(${\pm}$2.00), 장애는 12점 만점에 평균점수 8.63(${\pm}$1.87), 자기 효능감은 8점 만점에 평균점수 5.67(${\pm}$1.40), 예방행동은 36점 만점에 평균점수 21.02(${\pm}$4.73)이었다. 신종인플루엔자 예방행동에 유의하게 영향을 미치는 건강신념변수는 심각성, 감수성, 이득, 자기효능감으로 나타났고, 장애는 상관관계가 없는 것으로 나타났다. 각 변수들과 예방행동 간의 상관되는 순서는 이득(r=.303), 자기효능감(r =.271), 심각성(r =.222), 감수성(r =.206), 장애(r =-.007)순으로 나타났다. 지식이 높을수록(p<0.05), 예방교육을 받았던 대상자 일수록(p<0.05), 예방접종을 받을수록(p<0.05) 지각된 이득에 더 유의한 영향을 주는 것으로 나타났다. 본인의 건강상태가 좋다고 생각할수록(p<0.05), 지식이 높을수록(p<0.05), 예방교육을 받았던 대상자 일수록(p<0.05), 예방접종을 받을수록(p<0.05) 자기효능감이 높은 것으로 나타났으며, 건강신념변수들 간 상관관계에서 개인의 지각된 자기효능감과 지각된 이득 두 변수가 가장 높은 상관관계를 보였다(p<0.01). 위계적 회귀분석 결과 신종인플루엔자 예방행동에 영향을 미치는 요인 중 유의한 요인으로 인지된 이득(${\beta}$ =.179), 학년(${\beta}$ =.173), 자기효능감(${\beta}$ =.154), 인지된 심각성(${\beta}$ =.140), 예방교육경험(${\beta}$ =.111), 건강상태(${\beta}$ =.097)의 순으로 나타났다. 이상의 결과를 종합하면 건강신념모형이 신종인플루엔자 예방행동을 예측하고 교육목표와 내용을 결정하는데 있어 적합한 모형이라고 판단 할 수 있다. 건강신념모형 변수 중 이득과 자기효능감을 높일 수 있도록 프로그램과 교육목표를 설정하면 보다 효과적인 예방교육이 될 것이라 생각된다.

• Journal of the Korean Applied Science and Technology
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• v.37 no.5
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• pp.1344-1355
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• 2020

The purpose of this study was to investigate the relationship among trust of instructors, leisure benefit and resilience for golf participants. To achieve the goal of this study, a total of 250 questionnaires were distributed and 250 copies were collected back. Out of those returned questionnaires, insincerely replied or double-replied questionnaires were excluded and finally 234 questionnaires were analyzed for this study. For analysis of the data, frequency analysis, exploratory factor analysis, reliability analysis, confirmatory factor analysis, correlation analysis, and structural equating modeling were conducted using SPSS 18.0 and AMOS 18.0. Main findings were as follows: First trust of instructors had a positive effect on leisure benefit. Second, leisure benefit had a positive effect on resilience. Third, trust of instructors had a positive effect on resilience. Fourth, leisure benefit mediated the relationship between golf participant trust of instructors and resilience. Therefore, it is necessary to make efforts to make golf participation lead to satisfaction, and in addition, it is necessary to seek various and convenient services so that various benefits can be generated through golf, and even psychological management through careful observation of golf participants. Is judged.

• Journal of Aerospace System Engineering
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• v.15 no.5
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• pp.8-15
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• 2021

This paper describes a design method using an optimization technique to satisfy the longitudinal handling quality of high maneuverable jet aircraft. The dynamic inversion technique was applied to the target aircraft, and the control gain optimization satisfied the longitudinal short-period handling quality, however, the stability margin was not considered. If the stability margin is not satisfied, it is necessary to directly readjust the gains through trial and error methods for improvement. To improve this, an additional compensator and an optimization constraint were added to the control gain optimization procedure. In addition, the degree of handling quality satisfaction with the optimization result was reevaluated, and additional control evaluation criteria for the convergence of the time response and the steady state error that the flight performance requirement set as the optimization constraint cannot be reflected, and the results are described.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.97-98
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• 2016

본 논문은 위치, 속도, 전류 제어기들이 직렬로 연결된 전동기 구동시스템에서 속도 제어기를 사용하지 않는 위치 제어를 위한 PI-PD 제어기 설계법을 제안한다. 기존의 PI-PD 위치 제어기 설계법과 달리 제안된 제어기의 설계법은 위치 제어기의 대역폭에 따라 이득 값을 설정할 수 있다. 제안된 위치 제어기 설계 성능을 검증하기 위해 IPMSM 구동시스템에서 실험을 통해 유효성을 확인하였다.

• Korean Business Review
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• v.20 no.1
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• pp.145-168
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• 2007

Recommender system helps customers to find easily items and helps the e-biz companies to set easily their target customer by automated recommending process. Recommender systems are being adopted by several e-biz companies and from these systems, both of customers and companies take some benefits. This study sets several thresholds to the similarity weight, which indicates a degree of similarity of two customers' preference, to improve the performance of prediction accuracy. According to the threshold, the accuracy of prediction is being improved but some threshold setting shows the reduction of the prediction rate, which is the coverage. This coverage reduction has male effect on the prediction accuracy of customers, so more study on the prediction accuracy of recommender system and to maximize the coverage are needed.