• 오토저널
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• 제15권3호
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• pp.36-46
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• 1993

In CVT vehicle, the engine speed is completely decoupled from the vehicle speed within the range from maximum transmission ratio to minimum transmission ratio. This allows the engine to operate in optimal state(e.g. best fuel economy or maximum power mode.) In this study, the CVT control algorithm for optimal operation of engine is suggested. In order to implement the real time digital control of electro-hydraulic CVT system, a software called CVTCON has been developed. CVTCON also includes the CVT operation module, (2) system test module, (3) system control module and (4) data management module. By using the CVTCON and the electro-hydraulic CVT system, two modes of experiments were carried out: constant throttle opening mode and acceleration mode. From the experimental result, it was found that the algorithm suggested in this study showed optimal operation of the CVT system.

• 유공압시스템학회논문집
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• 제6권4호
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• pp.16-23
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• 2009

The major system of an agricultural shuttle power-shift tractor is the transmission, using power-shift. Because the shifting performance depends on the hydraulic control system, the most important aspect of the optimization is the design of the hydraulic control system. This study was conducted to develop the simulation model of hydraulic control system for the shuttle power-shift transmission by using Easy5 software. Bench test was conducted to verify the simulation. Also, the design parameters which influence the pressure modulation characteristics were investigated.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2006년도 추계학술대회 학술발표 논문집 제16권 제2호
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• pp.289-292
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• 2006

In this paper, a wireless control network based on IEEE 802.15.4 MAC protocol is proposed. The superframe of IEEE 802.15.4 is applied to the proposed wireless control network. The transmission and bandwidth management method are proposed for efficient transmission in the superframe. By these methods, the proposed wireless control network protocol is able to transmit three types of data (periodic data, sporadic data, and non real-time message), and guarantee real-time transmission within deadline.

• 드라이브 ㆍ 컨트롤
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• 제10권4호
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• pp.34-40
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• 2013

The transmission control method of small forklift is classified into pilot control method and direct control method. In pilot control method, the hydraulic circuit which consists a lot of components is very complex so the production process is too costly and time consuming. The direct control method contains fewer components that can be configured to simple hydraulic circuit. It has more advantages because the shift sensitivity of transmission is changed easily via the input profile. In this paper, the controller design and the input profile for system are studied to apply to the direct control method. The input profile consists of Fill section, Hold section and Ramp section. The characteristic of each section is obtained through experiment. As the result, the shift sensitivity and starting performance are effected by Fill section and Hold section.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.1255-1261
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• 2010

An operating information and fault recode of train is very important information for safety driving and maintenance. And these information is increased and need high speed as the number of trains is increased. Wireless LAN or CDMA network is efficient to report more complicated and various information from vehicle to server in control center. Existing wireless transmission system has weakness due to transmission system is separated with TDCS and standalone. At first, standalone system needs space to be installed and cost is increased. And data transmission capacity and speed is limited by complicated structure that transmission system receive data thru serial communication like RS232 and then data transmission system send data to server in control center. This article is study to develop embedded & wireless fault code transmission device to be installed in TDCS to overcome weakness of space and to have more cost effective and simple structure. It is adapted 802.11b/g WiFi for wireless communication and OS is used embedded Linux that can easily implement wireless communication environment and ensure TCP/IP communication’s security. We also implement simple server to test wireless communication between embedded & wireless fault code transmission device and server in control center.

• 융합신호처리학회논문지
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• 제22권2호
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• pp.64-70
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• 2021

최근 무선 네트워크 기반 실시간 원격제어에 대한 관심이 크게 증가하고 있다. 무선 네트워크를 통하여 실시간 원격 제어를 구현하는데 있어서, 중요한 요소들 중 하나가 실시간 제어메시지의 지연시간 성능이다. 특히, 주기적으로 송신되는 실시간 제어메시지의 안정적인 수신을 위해 지연시간 지터를 줄이는 기술이 필요하다. 본 논문에서는 실시간 제어메시지를 무선 네트워크에서 운용 하는데 있어서 지연시간 지터를 감소시키는 동기화 전송을 제안한다. 제안된 동기화 전송은 송신노드와 무선통신기 간의 동기화를 바탕으로 적절한 전송시점을 제어하여 실시간 제어메시지가 항상 정해진 시간에 무선 네트워크를 통하여 전송 되도록 한다. 군용무인차량 시스템을 이용한 실험 결과에 따르면, 제안된 동기화 전송은 지연시간 지터를 일반 전송 방식의 지연시간 지터의 32% 수준으로 감소시켰다.

• Parasites, Hosts and Diseases
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• 제60권5호
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• pp.317-325
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• 2022

Hypoxia-inducible factor-1 alpha (HIF-1α) is one of the master regulators of immune and metabolic cellular functions. HIF-1α, a transcriptional factor whose activity is closely related to oxygen levels, is a target for understanding infectious disease control. Several studies have demonstrated that HIF-1α plays an important role during the infectious process, while its role in relation to parasite virulence has not been addressed. In this work, we studied the expression levels of HIF-1α and related angiogenic vascular endothelial growth factor A (VEGF-A) in human macrophages infected with promastigotes of hypo- or hyper-virulent Leishmania major human isolates. L. major parasites readily subverted host macrophage functions for their survival and induced local oxygen consumption at the site of infection. In contrast to hypo-virulent parasites that induce high HIF-1α expression levels, hyper-virulent L. major reduced HIF-1α expression in macrophages under normoxic or hypoxic conditions, and consequently impeded the expression of VEGF-A mRNA. HIF-1α may play a key role during control of disease chronicity, severity, or outcome.

• 한국정보통신학회논문지
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• 제25권7호
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• pp.923-929
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• 2021

TCP 통신, 패킷통신은 고품질과 고신뢰성 확보를 위해서는 전송제어 기술이 필요하다. 그러나 실시간 데이터 전송의 경우 비효율적 전송 문제가 발생한다. 이러한 문제점을 극복하여 패킷의 신뢰성 전송을 위해 일반적으로는 단순히 버퍼 수위를 지표로 하는 조기혼잡제어를 사용 하였다. 혼잡을 제어하는 시점을 버퍼 수위에 기준을 두기 때문에 혼잡제어 시점과 해지 시점의 제어가 지연된다. 따라서 본 논문에서는 버퍼 수위 지표뿐만 아니라 네트워크 혼잡을 측정하는 전송 속도와 버퍼 수위가 최적의 설정 이상 수준에 근접하도록 패킷 폐기확률을 결정하는 이상적인 버퍼 수위와 함께 분류 하였다. 제안 방법을 입증하기 위한 실험에서 설정한 이상적인 버퍼 수위에 의해 평균버퍼 수위가 유지되게 함으로 직접 제어할 수 있음을 결과로 나타내었다.

• Journal of Mechanical Science and Technology
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• 제18권1호
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• pp.82-91
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• 2004

This article deals with a minimum energy control law of S-CVT connected to a dc motor. The S-CVT can smoothly transit between the forward, neutral, and reverse states without any brakes or clutches, and its compact and simple design and its relatively simple control make it particularly effective for mechanical systems in which excessively large torques are not required. And such an S-CVT equipped power transmission has the advantage of being able to operate the power sources in their regions of maximum efficiency, thereby improving the energy efficiency of the transmission system. The S-CVT was intended to primarily for use in small power capacity transmissions, thus a dc motor was considered here as the power source. We first review the structure and operating principles of the S-CVT, including experimental results of its performance. And then we describe a minimum energy control law of S-CVT connected to a do motor. To do this, we describe the results of an analysis of the dynamics of an S-CVT equipped power transmission and the power efficiency of a DC motor. The minimum energy control design is carried out via B-spline parameterization. And we show numerical results obtained from simulations illustrate the validity of our minimum energy control design, benchmarked with a computed torque control algorithm for S-CVT.

• 한국산업정보학회논문지
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• 제7권3호
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• pp.54-61
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• 2002

원격 영상전송 장치는 안전상의 문제가 있거나 사람이 갈 수 없는 곳을 관찰하기 위해 로봇 기술과 영상전송 기술을 결합한 것이다. 최근 원격 제어를 위해 웹서버와 로봇간 유선 및 RF를 이용한 제어 장치들이 개발되고 있지만, 작동 거리 및 인터넷 라인을 설치해야 하는 제한점이 있으며, 무선 방식의 통신장비를 이용할 경우 무선 라우터의 가격이 고가라는 문제가 있다. 본 연구에서는 이러한 문제점을 해결하기 위해 CDMA 셀룰러 폰 통신망을 이용하여 영상전송 및 영상전송 장치를 원격으로 제어할 수 있는 시스템을 개발하였으며, 개발된 시스템은 기존의 무선동신(RF)을 이용한 영상 전송시의 단점인 거리 제한 문제와 인터넷을 이용한 영상전송시의 문제를 해결할 수 있었고, 현재의 통신망을 비롯한 제한된 조건하에서 최적의 영상 및 음성을 전송할 수 있었다.