• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1993.04a
• /
• pp.86-92
• /
• 1993

자동차의 현가장치에 대한 능동제어연구는 국내외적으로 활발히 진행되어 왔다. 수동식현가장치는 단순히 스프링과 감쇠기로 차체의 진동을 수동 제어 하므로 성능 향상에 한계가 존재하게 된다. 수동식 현가장치가 강성계수와 감쇠계수를 조절함으로써 차체로 들어오는 진동을 억제하는 반면, 능동식제 어는 보통 유압을 이용하여 효율적으로 차체에 들어오는 진동을 억제시키게 된다. 일반적으로 자동차가 능동현가장치 설계시 요구되는 사항은 탑승자의 승차감, 조종성, 현가장치의 공간확보 문제, 경제성(제어력), 실제적으로 자동 차에 적용할 수 있는 능동제어기법인가 하는 문제이다. 자동차 능동식 현가 장치는 보통 1/4 car (2자유도계), Full-car 모델 (7자유도계) 등으로 모델링 을 하여 능동제어기를 설계한다. 1/4 car 모델의 특징은 해석이 비교적 단순 하고 현가장치의 동적거동을 이해하는데 유용하고 실험을 하거나 실제 자동 차에 적용하기 쉬운 반면에 Full-car 모델에 비해 제어력의 효율이 떨어진다 는 단점이 있다. 그 이유는 1/4 car 모델은 차체의 동역학적 특성을 고려하 여 설계하지 않았기 때문에 4개의 독립현가차축에서는 오직 그 현가축방향 으로 발생하는 수직방향의 진동만을 제어하기 때문이다. 따라서 동역학적 역 성에 기인하는 운동을 제어하는 비효율적인 제어력이 공급된다는 단점을 갖 는다. 이에 비해 full-car 모델은 주행모드(수직, 롤링, 피칭운동)간의 연성을 고려하여 제어기를 설계할 수 있기 때문에 1/4 car 모델에 비해 제어력의 효 율이 높다는 장점이 있는 반면에 모델이 수학적으로 복잡하므로 제어력을 구하는데 계산량이 많고, 실제 자동차에 적용하기에 복잡하다는 단점을 갖고 있다. 따라서 본 논문에서는 쉽게 실험할 수 있고, 실용화할 수 있는 1/4 car 모델에 대하여 능동제어기를 설계하여 실제자동차에 능동제어기를 적용할 때 참고가 될 수 있도록 하였다. 자동차는 저주파영역의 밴드통과필터 역할 을 하므로 저주파에서의 성능, 특히 탑승자가 민감하게 느끼는 0.5Hz - 10Hz 부근의 주파수성능은 승차감, 조종성에 상당히 중요하다. 이에 본 논문 에서는 0.5Hz - 10Hz 부근의 승차감, 조종성의 향상에 초점을 두고 차체의 속도를 출력변수로 한 LQG/LTR 제어기를 설계하였다. LQG/LTR 설계기법 은 안정도-강인성이 좋은 체계적인 설계기법으로서 전 상태를 측정할 필요 가 없으므로 실제 적용시 효과적이다. 또한 자동차의 제원의 변화에 대한 고 유치의 민감도해석과 새로운 개념으로 안정도-강인성(Robustness)해석을 하 여 수동시스템과 능동시스템의 강인성을 비교하였다.

• Proceedings of the KIEE Conference
• /
• 2007.10a
• /
• pp.247-248
• /
• 2007

컴퓨터의 발전은 철도 산업에 큰 영향을 끼치고 있다. 특히 기계식이나 수동식 신호 장치들이 마이크로프로세서를 탑재하면서 전자식, 자동식으로 변경되면서 철도 신호 시스템에 큰 변화를 가져왔다. 이로 인해 안전성은 더 높아지고 수송력 또한 증가하게 되었다. 이런 변화에 핵심적인 역할을 하는 것이 바로 열차집중제어장치이다 열차집중제어장치는 기본적인 역할은 운행되는 열차들의 운전정보를 획득하고 이 정보들을 이용하여 효율적으로 차량을 운행하게 제어하는 것이다. 하지만, 다양한 철도 차량들이 생겨나고 신호 시스템이 발전하게 되면서 열차집중제어장치도 더 다양한 기능과 처리 능력을 가지도록 설계되어져야 한다. 특히, 현재 큰 관심을 받고 있는 무인운전, 무선을 이용한 철도 시스템에서는 열차집중제어장치의 역할이 매우 중요한 부분이 되고 있다. 본 논문에서는 이런 상황을 고려하여 실시간으로 정보를 처리하고, 차량을 안전하게 제어하며, 모든 상황들을 정보화할 수 있는 열차집중제어장치에 대한 설계를 하고자 한다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.4 no.6
• /
• pp.515-522
• /
• 1999

Several power factor correction(PFC) circuits are presented to achieve high PF electronic ballast for both v voltage-fed and current-f,어 ek'Ctronic ballast. The proposed PFC circuits use valley-fil[(VF) type DClink s stages modified from the conventional VF circuit to adopt the charge pumping method for PFC operations d during the valley intervals. In voltage-fed ballast, charge pump capacitors are connected with the resonant c capaCltor In current-fed type, the charge pump capacitors are connc'Ctc'Cl with the additional second따y-side of t the power transformer. The measured PF is higher than 0.99 and THD is about 10% for all proposed PFC c circuits. The lamp current CF is also acceptable in the proposed circuits. The proposed circuit is suitable for i implementing cost longrightarroweffective electronic ballast.

• The Journal of the Korea Contents Association
• /
• v.20 no.6
• /
• pp.9-25
• /
• 2020

As laser scan and photogrammetry are extensively applied to 3D modeling, the Retopology has become a critically important part in the 3D modeling process. However, abundant time would be wasted if the wrong method for retopology is employed. This paper aims to select the most suitable method and software for retopology for different types of models so as to increase the effectiveness of 3D modeling. In this paper, retopology is divided into three types according to the existed software for retopology in the market: manual, automatic and wrapping type, all of which are investigated by their characteristics of retopology and software in which they are applied individually. Then case production is employed on Static Mesh Skeletal Mesh and Hard Surface Modeling by the above mentioned three methods. The advantages and disadvantages of the software in which the above three methods can be applied are summed up, and the manual type produces good results, the automatic type is fast, and the wrapping type requires a pre-existing base mesh and the most suitable method for retopology for each type of 3D models is demonstrated. This paper provides reference for retopology and increases the effectiveness of 3D modeling.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.12
• /
• pp.857-866
• /
• 2020

'Movement' is an expanded concept of 'place' where people act, interact with one another and achieve a specific purpose at every moment. Wheelchairs, as a mobility aid, have a profound impact on improving the quality of physical and psychological well-being for the mobility disadvantaged groups who have mobility difficulties. Such mobility aids were developed mainly for outdoor activities, but in recent years, mobility aids for indoor spaces, the main living environment, are also being developed. Because indoor mobility aids generally move short distances repeatedly, this study examined the characteristics of lithium-ion batteries in short-distance driving of battery-powered wheelchairs and compared them with the characteristics of lithium-ion batteries in continuous driving. The result showed that the driving time for short-distance driving was 2.8% shorter than that of continuous driving. The current supplied to the motor was 15.4% higher for short-distance driving than that of continuous driving.

• Journal of rehabilitation welfare engineering & assistive technology
• /
• v.7 no.1
• /
• pp.21-27
• /
• 2013

Manual wheelchair propulsion can lead to pain and injuries of users due to mechanical inefficiency of wheelchair propulsion motion. The kinetic analysis of the upper limbs during manual wheelchair propulsion needs to be studied. A two dimensional inverse dynamic model of upper limbs was developed to compute the joint torque during manual wheelchair propulsion. The model was composed of three segments corresponding to upper arm, lower arm and hand. These segments connected in series by revolute joints constitute open chain mechanism in sagittal plane. The inverse dynamic method is based on Newton-Euler formalism. The model was applied to data collected in experiments. Kinematic data of upper limbs during wheelchair propulsion were obtained from three dimensional trajectories of markers collected by a motion capture system. Kinetic data as external forces applied on the hand were obtained from a dynamometer. The joint rotation angles and joint torques were computed using the inverse dynamic model. The developed model is for upper limbs biomechanics and can easily be extended to three dimensional dynamic model.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.17 no.4
• /
• pp.540-545
• /
• 2007

In this thesis, we introduce and investigate new architectures and comprehensive design methodologies of intelligent dimming converter and evaluate the proposed model and the system through a series of numeric experiments. Electronic ballast enable prolongation of life foy Fluorescent-Lamp and ballast. However, There are no merit in case that user impossible manual control. Therefore in this paper, we put emphasis on the design of electronic ballast based on intelligent dimming converter and the energy saving according to the day-light and the user settings by applying the intelligent model to a fluorescent lamp. Also, we show the superiority of the proposed Intelligent dimming converter through the evaluation of performance with conventional electronic ballast by applying the intelligent model to hardware of systems.

• Journal of the Korean Geotechnical Society
• /
• v.23 no.4
• /
• pp.47-58
• /
• 2007

The usage of Integral abutment bridges has been increased worldwide because of reducing bridge maintenance costs and resisting seismic loads. Although these attributes make the integral abutment bridge an increasingly popular choice, back-abutment interaction issues remain unresolved. Hence, the earth pressure behavior of an integral abutment bridge having 90 m long PSC beam bridge for the first time in Korea was analyzed by conducting long term monitoring in this study. Based on this study, the results were as follows; the ratio of maximum passive movement to the abutment height (H) of 0.0027 and the maximum passive earth pressure coefficient of 4.8 were developed at 0.82H from the bottom of the abutment during summer season. During winter season, the ratio of maximum active movement to H of 0.0011 and the maximum active earth pressure coefficient of 0.7 were developed at the same location as in summer season. The new earth pressure distributions having a trapezoid type were proposed based on this study.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.4
• /
• pp.911-917
• /
• 2008

In this paper. we introduce and investigate new architectures and comprehensive design methodologies of intelligent dimming converter and evaluate the proposed model and the system through a series of numeric experiments. The intelligent dimming converter is developed by using the regression polynomial fuzzy model. In this paper, we put emphasis on the design of electronic ballast based on intelligent dimming converter and the energy saving according to the day-light and the user setting by applying the intelligent model to a fluorescent lamp. We show the superiority of the proposed intelligent dimming converter through the evaluation of performance with conventional electronic ballast by applying the intelligent model to real systems.

• Proceedings of the KIEE Conference
• /
• 2000.07d
• /
• pp.3175-3177
• /
• 2000

전압원과 전류원 및 RLC 수동소자들로 구성된 대형회로망에서 망(網)과 마디를 복합시킨 새로운 회로망 해석법을 제시하였다. 종래의 수식적 유도 과정이 불필요하며 도식적 추출에 의해 대형회로망을 간단히 해석한다 각 전원은 직렬 또는 병렬 임피던스를 반드시 수반하고 있지 않아도 무방하다. 망 설정과 마디 선정 과정에서의 전원 처리에 의해 회로망의 도형화 시켰고, 그로부터 행렬 형태의 부분 식을 도출하였다. 망해석법에 의한 방식과 마디해석법에 의한 기법이 가지전류방향 행렬에 의해 합성된다. 합성된 최종 식은 컴퓨터 몫이다.