모델 예측 제어 기법을 이용한 토크벡터링과 후륜조향 통합 제어

차현수,김자유,이경수 사단법인 한국자동차안전학회 2022 자동차안전학회지 Vol.14 No.4

This paper describes an integrated control of torque vectoring and rear wheel steering using model predictive control. The control objective is to minimize the yaw rate and body side slip angle errors with chattering alleviation. The proposed model predictive controller is devised using a linear parameter-varying (LPV) vehicle model with real time estimation of the varying model parameters. The proposed controller has been investigated via computer simulations. In the simulation results, the performance of the proposed controller has been compared with uncontrolled cases. The simulation results show that the proposed algorithm can improve the lateral stability and handling performance.

시각장애 초등학생 학습을 위한 수평잡기 저울의 개발

차현수,박종호,백남권 한국물리학회 2009 새물리 Vol.58 No.4

The purpose of this study is to develop a horizontal balance for visually-handicapped elementary students. According to elementary 4th-grade curriculum of the current 7th science subject, the experiment with a horizontal balance reflects putting some pieces of wood on a board (on the balances) and observing the inclination degree; thus, generally, it is available to normal elementary students only. This experiment is difficult for those without sight, who rely mainly on the senses of touch and hearing to perform and analyze an experiment. Thus, in order to solve this problem, we put some sound devices on the experimental apparatus. This experiment, using the horizontal balance we had made, was conducted with those who had low vision and achromatopsia. To test the excellence and independency in the experiment, we chose Busan School of the Blind; and only then, we chose only seven students with a simple visual handicap from among students in the 3th to 6th grades for the experiment and counseling. We obtained educationally satisfactory results through this experiment. 시각장애 초등학생용 수평잡기 거울을 제작하여 시각장애 초등학생들을 대상으로 실험하였다. 현행 제7차 과학과 교육과정의 초등학교 4학년에 나오는 수평잡기 개념 실험은 기울어지는 정도를 관찰하면서 널빤지에 나무도막을 올려놓는 것이다. 일반적으로 정상인에게만 가능하다. 그러나 시각적 관찰에 어려움이 있는 시각장애 초등학생들은 수평잡기 실험과 관찰에 어려움을 겪는다. 이러한 점을 보완하기 위하여 기존의 수평잡기 실험 기구에 소리가 나는 기구를 부착하여 시각장애 초등학생용 수평잡기 실험기구를 제작하였다. 제작된 실험기구의 적용가능성에 대해서는 부산 소재 맹학교 저시력과 전맹 시각장애 초등학생들에게 실험하였다. 실험 결과 본 연구자들이 제작한 수평잡기 저울은 현장에 충분히 적용 가능한 교육적으로 만족한 결과를 얻었다.

USN 의 전송 계층 프로토콜에서 에러 및 흐름제어의 성능 평가

차현수,강철균,유승화,김기형 한국정보통신설비학회 2008 한국정보통신설비학회 학술대회 Vol.2008 No.1

Many applications of sensor network require connection to the Internet. The transmission protocol of traditional sensor network was designed within the sensor network itself. However, based on 6LoWPAN which can be accessed using IPv6, direct connection is possible between the sensor network and the TCP/IP network outside. Transmission of data in ap plications of sensor network falls into two main categories. One is a small packet that is periodically produced such as pa cket related to temperature and humidity. The other is a relatively large packet that brings about network overheads such as images. We investigated the conformance test and pros and cons of application data over the transmission protocol of Z igbee and 6LoWPAN. As a result, both Zigbee and 6LoWPAN have shown low rate of loss for periodic data and have in creased reliability of data transfer. When transmitting streaming image data, both ACK, non ACK mode of Zigbee and UD P of 6LoWPAN minimized transmission time but suffered the consequences of high packet loss. Even though TCP of 6Lo WPAN required a long transmission time, we were able to confirm that no loss has occurred.

전륜 인휠모터 후륜구동 차량의 선회 특성 변형을 위한 요모멘트 제어

차현수,좌은혁,박관우,이경수,박재용 사단법인 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.1

This paper presents yaw moment control for modification of steering characteristic in rear-driven vehicle with front in-wheel motors (IWMs). The proposed control algorithm is designed to modify yaw rate response of the test vehicle. General approach for modification of steering characteristic is to define the desired yaw rate and track the yaw rate. This yaw rate tracking method can cau se the chattering problem becau se of the IWM actuator response. Large overshoot and settling time in IWM torque response can amplify the oscillation in control input and yaw rate. To resolve these problems, open-loop IWM controller for cornering agility was designed to modify the understeer gradient of the vehicle. The proposed algorithm has been investigated via the computer simulations and the vehicle tests. The performance evaluation has been conducted on dry asphalt using E-segment test vehicle. The performance of the proposed algorithm has been compared to general yaw rate tracking algorithm in the vehicle tests. It has been shown that the proposed control law improved the cornering agility without chattering problem.

재전송 메커니즘에 의한 SIP 등록 취소 및 통화 방해 공격 대응 방안

차현수,류제택,노병희,정현철 한국차세대컴퓨팅학회 2008 한국차세대컴퓨팅학회 논문지 Vol.4 No.3

SIP는 상호 간의 멀티미디어 통신 세션을 관리하는 응용 계층 시그널링 프로토콜이다. 현재 SIP는 프로토콜의 간편성, 유연성, 다양성 등의 장점을 가지고 인터넷 메신저, 게임, VoIP(Voice over IP)등에 널리 이용되고 있다. 그러나 SIP는 여러 보안상의 문제점들을 가지고 있고, 특히 통화 방해 공격은 사용자들에게 큰 불편을 줄 수 있는 공격으로 이에 대한 대응 방법이 요구된다. 따라서 본 논문에서는 SIP 등록 취소 공격 및 통화 방해 공격에 대해서 분석해보고 이를 탐지 하는 기법을 제안한다. 공격 탐지는 재전송 메커니즘을 기반으로 공격으로 의심되는 메시지와 사용자가 마지막으로 전송한 메시지의 비교를 통해서 이루어진다. 만약 메시지가 공격으로 판단될 경우 사용자에게 이를 알리고 재인증 과정을 거친다. SIP is an application-level signaling protocol that manages a mutual multimedia communication session. Presently, SIP is widely used with internet messaging, games and with VoIP (Voice over IP) due to advantages such as its simplicity, flexibility and variety of protocols. However, SIP is associated with many types of security issues and requires a countermeasure device against call-disturbance attacks that can cause a great amount of inconvenience to users. Therefore, this study analyses SIP De-registration and call-disruption attacks and proposes a means of detecting these attacks. Attack detection is accomplished through a comparison of the messages last sent by the user and those that are considered to be an attack based on a Retransmission mechanism. When a message is detected as an attack, the user is informed and a Reauthentication process is performed.

전자식 차동 제한장치를 이용한 후륜구동 차량의 횡방향 안정성 제어

차현수,이경수,Cha, Hyunsoo,Yi, Kyongsu 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.3

This paper presents a lateral stability control for rear wheel drive (RWD) vehicles using electronic limited slip differentials (eLSD). The proposed eLSD controller is designed to increase the understeer characteristic by transferring torque from the outside to inside wheel. The proposed algorithm is devised to improve the lateral responses at the steady state and transient cornering. In the steady state response, the proposed algorithm can extend the region of linear cornering response and can increase the maximum limit of available lateral acceleration. In the transient response, the proposed controller can reduce the yaw rate overshoot by increasing the understeer characteristic. The proposed algorithm has been investigated via computer simulations. In the simulation results, the performance of the proposed controller is compared with uncontrolled cases. The simulation results show that the proposed algorithm can improve the vehicle lateral stability and handling performance.

패밀리 레스토랑의 전환장벽이 충성도와 고객유지에 미치는 영향

차현수,박종원,강도원 한국마이스관광학회 2014 MICE관광연구 Vol.14 No.S2

The purpose of this study is to investigate Switching Barriers of Family Restaurant. Influencing Customer retention, Loyalty, and to perform the empirical analysis. Switching barrier can help firm attract new customers or retain old customers, because it could keep relationships between users and suppliers. Switching barriers is an important marketing strategy in family restaurant industry in the face of increasing competitions. In this study switching barrier was divided into positive switching barrier and negative switching barrier. Then the influence of positive or negative switching barrier on customer retention and customer loyalty is analyzed. The results are as follows: First, Positive switching barrier is related to active loyalty, passive loyalty, and customer retention. Second, Negative switching barrier influences only passive loyalty negatively. These results remained that negative switching barrier, like money, has no affection to family restaurant users.

간호대학생의 SNS 중독 경향성이 대학 생활 적응에 미치는 영향

차현수 한국산학기술학회 2020 한국산학기술학회논문지 Vol.21 No.11

이 연구의 목적은 SNS 중독 경향성이 간호대학생의 대학 생활 적응에 미치는 영향을 파악하고, 대학 생활 적응을 향상시키기 위한 프로그램의 기초자료를 제공하기 위함이다. 자료는 전라남도와 경기도에 소재한 2개 대학교 간호대학생 255명을 대상으로 2020년 5월 16일부터 5월 20일까지 자기 기입식 설문지로 설문 조사하여 수집하였다. 자료는 SPSS 23.0 program (frequency, pearson’s correlation, ANOVA, multiple regression) 으로 분석하였다. SNS 중독 경향성 평균점수는 2.16±0.54점 (범위:1-5점) 이었다. 대학 생활 적응 평균점수는 3.13±0.39점 (범위:1-5점) 이었다. 대학 생활 적응에 SNS 중독 경향성은 부적 영향을 미쳤다. 대학 생활 적응의 하위영역 중 ‘대학에 대한 애착’에 SNS 중독 경향성이 부적 영향을 미쳤다. SNS 중독 경향성은 대학 생활 적응에 27%의 설명력을 보였다. 이 연구의 결론은 SNS 중독 경향성이 간호대학생의 대학 생활 적응에 부적인 영향을 미친다는 것이다. 향후 간호대학생의 대학 생활 적응을 향상시키기 위해 SNS 중독 경향성을 치료하는 프로그램을 마련해야 하며, 치료를 시작해야 하는 SNS 중독 경향성 기준점을 파악하는 연구가 이루어져야 할 것이다. The purpose of this study was to understand the influence of social network site (SNS) addiction on the ability of nursing students to adjust to university life and to generate the basic data to develop programs that could improve this ability. The data was collected from questionnaires that were filled out by 255 nursing students in two universities located in Jeollanam-do and Gyeonggi-do from May 16, 2020 to May 20, 2020. The data was analyzed using the SPSS 23.0 program (frequency, ANOVA, Pearson's correlation, multiple regression). The mean scores of SNS addiction and adjustment to university life were 2.16±0.54 (range:1-5) and 3.13±0.39 (range:1-5) respectively. SNS addiction accounts for 27% of the variance in adjustment to university life. The study concluded that SNS addiction negatively affects adjustment to university life among nursing students. To ensure better adjustment a program should be developed to treat SNS addiction early. Also, a study will have to be conducted to determine the time when tendency toward SNS addiction becomes apparent, to initiate treatment.

시각장애학생의 이해를 위한 비장애학생들의 과학 시각장애 체험활동

차현수,박종호 한국물리학회 2011 새물리 Vol.61 No.4

In this study, scientific experiential activities for students with a sight disability were provided,together with experimental tools for the blind, to the elementary-school students who had no physical disability in order to help them to understand students who had a sight disability and to investigate their basic awareness of those students, elementary-school students in the fifth grade were chosen from Gyeongsangnam-do, Hadong-gun for the experiential activities. In the study, an investigation of the basic awareness about students who had a sight disability, scientific experiential activities for students with a sight disability, and a simple post investigation for participation in the activities were executed. In the investigation of the bagic awareness about students with a sight disability, we found that the students who had no physical disability lacked experience about the blind. Also, they seemed to have received no experiential education on sight disability. The scientific experiential activities for sight disability along with manufactured experimental tool for the blind, based on such experiments as counterbalancing, speed measurements and experiments for shades and lenses within the field of energy in the elementary-school science curriculum, were applied to students who had no physical disability. After taking part in the scientific experiential activities for students with a sight disability, the students with no physical disability showed a positive response towards those with a sight disability. 본 연구에서는 비장애학생들의 시각장애학생들에 대한 기초인식조사와비장애학생들이 시각장애학생들을 이해하는데 도움을 주기 위해서초등학교 과학실험을 시각장애인용 실험기구를 이용하여비장애학생들에게 과학 시각장애 체험활동을 실시하였다. 과학 시각장애체험활동은 경남 하동군의 초등학생 5학년 29명을 대상으로 하였으며,연구는 시각장애학생들에 대한 기초적인 인식조사, 과학 시각장애체험활동, 체험 후 활동참가에 대한 간단한 사후 검사를 하였다. 시각장애에 대한 기초조사에서 비장애학생들은 시각장애인에 대한경험부족과 시각장애체험교육을 받지 못한 결과로 나타났다. 과학시각장애 체험활동은 초등학교 과학교과의 에너지 영역에서 다루고 있는수평잡기, 속력측정, 그림자 실험, 렌즈실험을 시각장애인용 실험기구를제작하여 비장애학생들에게 적용하였다. 과학 시각장애 체험활동 후학생들은 시각장애학생들에 대해 긍정적 반응을 보였다.

타이어 힘 추정을 위한 파라미터 최적화 파제카 모델과 인공 신경망 모델 간의 비교 연구

차현수,김자유,이경수,박재용,Cha, Hyunsoo,Kim, Jayu,Yi, Kyongsu,Park, Jaeyong 한국자동차안전학회 2021 자동차안전학회지 Vol.13 No.4

This paper presents a comparative study between the parameter-optimized Pacejka model and artificial neural network model for the tire force estimation. The two different approaches are investigated and compared in this study. First, offline optimization is conducted based on Pacejka Magic Formula model to determine the proper parameter set for the minimization of tire force error between the model and test data set. Second, deep neural network model is used to fit the model to the tire test data set. The actual tire forces are measured using MTS Flat-Track test platform and the measurements are used as the reference tire data set. The focus of this study is on the applicability of machine learning technique to tire force estimation. It is shown via the regression results that the deep neural network model is more effective in describing the tire force than the parameter-optimized Pacejka model.