• 자동차안전학회지
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• 제15권3호
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• pp.17-26
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• 2023

This paper presents extended state feedback control based on impulse response for lane change of autonomous driving vehicle. The triple characteristic root of path tracking system and longitudinal velocity determine feedback gains. We suggest a resemblance of impulse response curve of the system and lane change trajectory of the vehicle. The root affects the duration of lane change and lateral acceleration. The effect of limited lateral acceleration and saturation of steering angle will be analyzed and discussed. Finally, simulation results will show the trajectory of lane change based on impulse response under limitation of lateral acceleration.

• 인터넷정보학회논문지
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• 제21권4호
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• pp.77-85
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• 2020

본 연구는 학생들의 성장에 따른 미디어 교육 활용 특성 종단적 변화를 알아보고자 하였다. 이를 위해 미디어의 교육적 활용 특성을 학습이용, 정보이용, 그리고 게임이용으로 구분하였다. 잠재성장모형을 적용하여 학습이용, 정보이용, 게임이용의 종단적 변화를 탐색하였다. 이후 3가지 미디어 교육적 활용 특성의 종단적 변화에서 성별 차이를 검증하였다. 한국청소년패널조사(KYPS)의 중등2패널을 활용하여 4년간 반복 추적 조사한 3,499명의 데이터를 분석하였다. 연구결과 (a) 학년이 증감함으로써 미디어의 학습이용과 정보이용의 변화율은 증가하는 경향을 나타내었다. (b) 여학생의 미디어 학습이용과 정보이용의 초기치와 변화율이 높은 것으로 나타났다. (c) 학년이 증가함으로써 미디어의 게임이용은 변화율이 감소하는 것으로 나타났다. (d) 미디어 게임이용에서는 초기치에는 남학생이 여학생보다 높은 것으로 나타났으나, 변화율에는 유의한 차이가 없는 것으로 나타났다.

• 아동학회지
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• 제30권4호
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• pp.69-85
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• 2009

The purpose of this study was to identify developmental trajectories of externalizing problems in preschoolers and to investigate dimensions of temperament and parental behaviors associated with trajectory groups. Subjects were 180 3- to 5-year-old preschoolers (96 males, 84 females) in the metropolitan area of Seoul. They were assessed three times at 5 month intervals over a one year period. Teachers reported on children's behavior problems, and parents reported on children's temperaments. Latent Growth Curve Modeling Analysis with cohort sequential design revealed externalizing behaviors gradually decreased between 3 and 6. At the 6-year-old level externalizing behaviors were associated with high novelty seeking temperament. The results were discussed in terms of the importance of longitudinal research in developmental psychopathology.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.728-731
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• 2003

This paper deals with a flat type ultrasonic motor, which uses a longitudinal-bending multi mode vibrator of rectangular form. A linear ultrasonic motor was designed by combination of the first longitudinal and eighth bending mode, and the motor consisted of a straight aluminum alloy bar bonded with piezoelectric ceramic elements as a driving element. The geometrical dimensions of the rectangular aluminum vibrator were determined by Euler-Bernoulli theory ANSYS was used to analyze the resonance frequency and the displacement of the stator vibrator. The resonance frequency of the motor provides the elliptical motion. and ANSYS was used to analyze elliptical motion and elliptical trajectory of stator vibrator when thickness of piezoelectric ceramics was varied respectively 0.763, 1.526, 2.289[mm] and width of stator vibrator was varied respectively 16, 12, 8, 4[mm]. When thickness of piezoelectric ceramics was decreased, the displacement of the stator vibrator was increased. And when width of stator vibrator was decreased, the displacement of the stator vibrator was increased.

• 대한가정학회지
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• 제49권9호
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• pp.59-72
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• 2011

This study examined whether there are underlying latent classes of growth trajectories of maternal depression in the Korean population. Data from the first phase of the Panel Study of Korean Children (PSKC) of the Institute of Child Care and Education (KICCE) were used for this study. The final sample of participants included 1,471 mothers, who completed three interviews: at birth, at one month, and at four months. A two-class model consisting of depression (12.3%) and non-depression (87.7%) was considered the best-fitting solution using Mplus 3.13. The changes in postnatal depression in the Korean population within four weeks after childbirth, which is the period of "postpartum onset", seem to be important. Logistic regression analysis showed that duration of breast-feeding and planned pregnancy effects were significantly associated with trajectory class membership.

• 한국수소및신에너지학회논문집
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• 제12권1호
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• pp.51-63
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• 2001

In this paper molecular dynamics simulations were employed to investigate the structural and dynamic properties of hydrogen ions impacted on the Ni (100) surface with the $45^{\circ}$ incident angle. The initial kinetic energies of the hydrogen ion range from 100 to 1,600 eV. Together with the trajectory visualization of hydrogen ions, we computed scattering and penetration yields, mean energies and angles, and probability and energy distributions as a function of longitudinal and azimuthal directions. In the case of lower energy scattering ions, the multiple collision effects were found to be important to the third layers or lower. For higher energy penetrating ions, compared with the normal incident angle, it was significant the effective channeling effects through the Ni layers and the angle dependencies were indicated both in the longitudinal and the azimuthal angle directions.

• 한국조사연구학회지:조사연구
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• 제12권2호
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• pp.113-144
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• 2011

본 연구의 목적은 청년 취업자의 직무만족도와 이직의사의 다양한 변화형태를 추정하여 잠재계층을 분류하고, 두 변수에 영향을 미치는 직무적합도(전공적합도, 교육수준적합도, 기술수준적합도)와의 효과를 밝히는 것이다. 이를 위하여 청년패널 2001의 만 15∼29세 청년 취업자를 대상으로 한 2001년부터 2006년까지의 종단자료를 이용하였다. 직무만족도와 이직의사의 잠재계층을 동시에 도출하기 위해 준모수적 집단중심 접근 방법의 확장모형인 이중 변화형태 모형(dual trajectory model)을 적용하였다. 분석 결과, 직무만족도 변화에 따른 잠재계층은 4개로 분류되었고, 변화형태에 따라 증가집단, 감소집단, 중간수준집단, 고수준집단으로 명명하였다. 이직의사 변화에 따른 잠재 계층은 3개로 분류되었고, 변화형태에 따라 저수준집단, 유지집단, 급감소집단으로 명명하였다. 직무만족도와 이직의사에 시간의존적 변수인 전공적합도, 교육수준적합도, 기술수준 적합도의 영향력을 검증한 결과, 직무만족도가 낮거나 이직의사가 높은 집단에는 교육수준 적합도 또는 기술수준적합도의 영향력이 유의하게 나타났다. 본 연구는 오랜 기간 직무만족도가 낮거나 이직의사를 지속적으로 가지고 있는 청년 취업자들을 위한 대책을 마련하는데 도움을 줄 것이다. 또한 잠재계층 모형을 확장시켜 두 가지 변수의 잠재계층을 동시에 도출하고, 그 잠재계층을 결정짓는 데 미치는 시간의존적 독립변수의 효과를 검증하는 종단연구 방법을 적용했다는 점에서 연구방법론적 측면에서 의의가 있다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.57-62
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• 2004

This paper deals with a waypoint trajectory following problem for the tilt-rotor UAV under development in Korea (TR-KUAV). In this problem, dynamic model inversion based on the linearized model and Sigma-Phi neural network with adaptive weight update are involved to realize the waypoint following algorithm for the vehicle in the helicopter flight mode (nacelle angle=0 deg). This algorithms consists of two main parts: outer-loop system as a command generator and inner-loop system as stabilizing controller. In this waypoint following problem, the position information in the inertial axis is given to the outer-loop system. From this information, Attitude Command/Attitude Hold logic in the longitudinal channel and Rate Command/Attitude Hold logic in the lateral channel are realized in the inner-loop part of the overall structure of the waypoint following algorithm. The nonlinear simulation based on the TR-KUAV is carried out to evaluate the stability and performance of the algorithm. From the numerical simulation results, the algorithm shows very good tracking performance of passing the waypoints given. Especially, it is observed that ACAH/RCAH logic in the inner-loop has the satisfactory performance due to adaptive neural network in spite of the model error coming from the linear model based inversion.

• 한국도로학회논문집
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• 제14권6호
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• pp.159-165
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• 2012

PURPOSES : The lack of details of guidelines on how to install the Chicane for traffic calming leads the practical difference across the calming areas, so the benefits expected from these facilities are not hardly observed. In this context, this study analysed the relationship between the geometric design alternatives of Chicane with the dynamic behaviour of vehicles in terms of speed and trajectory. METHODS : The study analysed vehicle dynamic behaviour using dynamic analysis program Auto-Turn under various geometric conditions of Chicane. RESULTS : This study suggested the design alternatives of Chicane using terms such as "longitudinal displacement value", "lateral displacement value", etc. which are defined in the study. The suggested combination set is fulfilling the desired or target speed of vehicles and clearance between vehicle and roadside at the same time. CONCLUSIONS : The results from this study can be applied to install Chicane corresponding to the local condition where target speed is 30km/h. The study showed the design alternatives of chicane corresponding to the given road cross-sectional design and clearance to roadside for passenger cars and light truck respectively.

• 대한간호학회지
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• 제33권5호
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• pp.562-569
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• 2003

Purpose: The purpose of this longitudinal prospective study was to assess changes in fatigue and quality of life for a 6-week course of radiotherapy. Method: A descriptive and longitudinal design was used to this study. Twenty-three subjects receiving radiotherapy from a radiotherapy clinic of a general hospital completed the questionnaires. Fatigue was measured using Lee's scale(1999) and quality of life using Yang's scale(2002) weekly for 6 weeks. Result: Fatigue significantly increased(F=6.043, p=.000), and quality of life significantly decreased (F=3.938, p=.003) and physical symptoms also significantly increased(F=2.432, p=.039) during a 6-week radiotherapy. Multiple regression analysis revealed that fatigue at the first week and physical symptoms at the 6th week were the significant affecting variables(60.1% of the variance) on fatigue. And 63.2% of the variance in quality of life was explained by quality of life and fatigue at the first week and body weight change for 6 weeks radiotherapy. Conclusion: Based on these results, the fatigue and quality of life at the beginning time of radiotherapy have a lasting impact throughout the course of treatment. It suggests that nurses provide patients with information about the occurrence of fatigue during radiotherapy and the practical methods of intervening physical symptoms.