• 한국자동차공학회논문집
• /
• 제22권3호
• /
• pp.42-49
• /
• 2014

The gasoline direct injection (GDI) system is considerably spreading in automotive market due to its advantages. Nevertheless, since GDI system emit higher particle matter (PM) due to its combustion characteristics, it is difficult to meet strengthened emission regulation in near future. For this reason, a combined GDI with MPI system, so-called, dual injection (DUI) system is being investigated as a supplemental measure for the GDI system. This paper focused on power and fuel consumption effect by injection mode strategy of DUI system in part load and idle engine operating condition. In this study, port fuel injectors are installed on 2.4 liters GDI production engine in order to realize DUI system. And, at each injection mode, DOE (design of experiment) method is used to optimize engine control parameters such as dual injection ratio, start of injection timing, end of injection timing, CAM position and so on. As a consequence, DUI mode shows slightly better or equivalent fuel efficiency compared to conventional GDI engine on 9 points fuel economy mode as well as MPI mode shows less fuel consumption than GDI mode during idle operation. Furthermore, DUI system shows improvement potential of maximum 2.0% fuel consumption and 1.1% performance compared to GDI system in WOT operating condition.

• 수면정신생리
• /
• 제8권2호
• /
• pp.138-143
• /
• 2001

Sleepiness is associated with many different conditions and, as a neglected topic, it can be the cause of serious psychological and social disadvantages. In the aspect of learning, additional problems may arise from poor progress in school caused by the effect of sleepiness on concentration, memory, and other cognitive functions. Narcolepsy is by no means the most common cause of excessive sleepiness. Nonetheless, it is not a rarity, especially in young people. The non-specific nature of early features of narcolepsy, combined with very limited awareness that the condition can start in various ways, leads to many misinterpretations. Misinterpretation of narcolepsy symptoms is not confined to the medical profession. Teachers may well be critical of a student with narcolepsy because of their perception of narcolepsy symptoms as laziness, poor motivation, or difficult behavior and dull learning ability. Inappropriate reactions by parents, teachers, and peers, based on misinterpretation of narcolepsy symptoms or the patient's reactions to them, make a difficult situation worse. Especially in Korea, where schooling is focused on college entrance examinations, the problem is very serious and intensified by inappropriate or delayed diagnosis and treatment. Therefore, psychiatrists should be aware that narcolepsy in young adolescents is not rare and that they need to be familiar with its clinical features in both its classic and less obvious forms. Narcolepsy should be suspected if a adolescent's excessive sleepiness can not be explained in other ways. Therefore, we report on two patients who portray the tendency of dull learning ability and are mistaken as idle students. We diagnosed narcolepsy through polysomnography and multiple sleep latency testing. We treated the students with methylphenidate and pemolin. The students showed improvement in learning ability and were able to adapt better to school.

• 한국정보통신학회:학술대회논문집
• /
• 한국정보통신학회 2019년도 춘계학술대회
• /
• pp.413-415
• /
• 2019

본 논문에서는 공유경제를 위한 IoT 기반의 휴먼 인터랙티브 광고 서비스(IoT-HiAS, IoT-Human Interactive Advertising Service)를 구현한다. HiAS 디바이스가 웹캠을 통해 디바이스의 전방을 촬영하고 MobileNet을 사용한 SSD 모델을 통해 사람을 실시간으로 검출한다. 검출된 사람을 카운팅하여 설정한 기준 이상의 사람 수가 검출되면 빔 프로젝터를 통해 유휴자원에 광고를 재생한다. 광고가 재생됨과 동시에 디바이스 전방의 광고 시작 시점을 캡쳐한 이미지와 검출된 사람의 수를 IoT 클라이언트를 통해 HiAS 서버의 oneM2M 표준을 준용한 IoT 서버로 전송한다. 광고가 끝나면 디바이스 전방을 촬영하여 이미지를 IoT 서버로 전송한다. 전송받은 데이터를 HiAS 서버의 소셜 네트워크 서비스(SNS, Social Network Service) 에이전트를 통해 광고주 및 광고제작자에게 알림 메시지를 전송하여 IoT 기반의 휴먼 인터랙티브 광고 서비스를 구현하였다.

• 한국자동차공학회논문집
• /
• 제8권4호
• /
• pp.26-33
• /
• 2000

In-cylinde flow and mixture formation are key contributors to both idle stability and combustion stability at part load condition in SI engine. The real time measurements of air-fuel ration and in- cylinder residual gas fraction are particularly important to obtain a better understanding of the mechanisms for combustion and emissions especially during cold start and throttle transient condition. This paper reports the cycle resolved measurements of residual gas fraction and equivalence ration near speak plug with value timing change and their effects on combustion characteristics at part load. The results showed that the effect of intake value opening on the residual gas fraction was smaller than that of exhaust valve closing because of the decreases of exhaust gas reverse flow from exhaust port. The variation of equivalence ratio near spark plug increased with the increase of value overlap and it closely related with heat release rate and combustion stability

• 전력전자학회논문지
• /
• 제19권2호
• /
• pp.139-148
• /
• 2014

State-of-charge (SOC) is one of the significant indicators to estimate the driving range of the electric vehicle and to control the alternator of the conventional engine vehicles as well. Therefore its precise estimation is crucial not only for utilizing the energy effectively but also preventing critical situations happening to the power train and lengthening the lifetime of the battery. However, lead-acid battery is time-variant, highly nonlinear, and the hysteresis phenomenon causes large errors in estimation SOC of the battery especially under the frequent discharge/charge. This paper proposes a novel estimation technique for the SOC of the Lead-Acid battery by using a well-known Extended Kalman Filter (EKF) and an electrical equivalent circuit model of the Lead-Acid battery considering diffusion and hysteresis characteristics. The diffusion is considered by the reconstruction of the open circuit voltage decay depending on the rest time and the hysteresis effect is modeled by calculating the normalized integration of the charge throughput during the partial cycle. The validity of the proposed algorithm is verified through the experiments.

• International Journal of Automotive Technology
• /
• 제8권4호
• /
• pp.437-444
• /
• 2007

This paper experimentally investigates the effects of oxygen-enriched air (OEA) on the running behaviors of an LPG SI engine during both start/warm-up (SW) and hot idling (HI) stages. The experiments were performed on an air-cooled, single-cylinder, 4-stroke, LPG SI engine with an electronic fuel injection system and an electrically-heated oxygen sensor. OEA containing 23% and 25% oxygen (by volume) was supplied for the experiments. The throttle position was fixed at that of idle condition. A fueling strategy was used as following: the fuel injection pulse width (FIPW) in the first cycle of injection was set 5.05 ms, and 2.6 ms in the subsequent cycles till the achieving of closed-loop control. In closed-loop mode, the FIPW was adjusted by the ECU in terms of the oxygen sensor feedback. Instantaneous engine speed, cylinder pressure, engine-out time-resolved HC, CO and NOx emissions and excess air coefficient (EAC) were measured and compared to the intake air baseline (ambient air, 21% oxygen). The results show that during SW stage, with the increase in the oxygen concentration in the intake air, the EAC of the mixture is much closer to the stoichiometric one and more oxygen is made available for oxidation, which results in evidently-improved combustion. The ignition in the first firing cycle starts earlier and peak pressure and maximum heat release rate both notably increase. The maximum engine speed is elevated and HC and CO emissions are reduced considerably. The percent reductions in HC emissions are about 48% and 68% in CO emissions about 52% and 78%; with 23% and 25% OEA, respectively, compared to ambient air. During HI stage, with OEA, the fuel amount per cycle increases due to closed-loop control, the engine speed rises, and speed stability is improved. The HC emissions notably decrease: about 60% and 80% with 23% and 25% OEA, respectively, compared to ambient air. The CO emissions remain at the same low level as with ambient air. During both SW and HI stages, intake air oxygen enrichment causes the delay of spark timing and the increased NOx emissions.

• 대한전자공학회논문지TE
• /
• 제39권1호
• /
• pp.55-64
• /
• 2002

이동전화 서비스에 있어서 가장 중요한 것 중 하나가 핸드오프(H/O :Hand-Off)이다. 그동안 동일 세대간(2G↔2G) H/O를 위해 소프트 H/O방식과 소프터 H/O방식이 이용되어 왔으며 별다른 문제점이 없었다. 그러나 사용자의 욕구와 통신기술의 발달로 세대가 다른 시스템이 공존하여 서비스를 시작하므로써 세대간(2.S↔2G) H/O를 위해 파이롯 비컨방식과 주기형 비컨방식이 이용되어 왔으나 비경제적이고 능률적이지 못하였다. 이를 개선하기 위해 2001년 4월 ENHHO방식이 개발되어 현재 이용되고 있다. 이 방식 또한 파이롯 신호가 5개 이상인 경우 H/O가 진행되는 동안 통화정보가 순간적으로 단절되는 단점을 갖고 있다. 따라서 본 논문에서는 ENHHO방식의 문제점을 개선하기 위한 알고리즘을 제안하고 이를 이용한 현장측정 결과를 분석하므로써 그 타당성을 검증하였다.

• 대한전자공학회논문지SD
• /
• 제47권9호
• /
• pp.1-6
• /
• 2010

H.264 영상 압축 표준은 높은 압축률과 화질로 널리 이용되고 있다. H.264 복호기는 일반적으로 마크로블록 또는 $4{\times}4$ 하위 블록 단위로 파이프라인을 적용하여 동작한다. 이러한 파이프라인 한 단의 주기는 보통 최악의 상황에서도 동작을 보장하도록 결정되어 높은 전송 대역폭과 고성능 연산기를 요구하고 연산기가 일을 하지 않고 쉬는 사이클이 많아지는 결과를 초래한다. 본 논문에서는 이러한 연산기의 쉬는 사이클을 줄이고 데이터 전송 대역폭과 연산기 성능 요구 조건을 완화시킬 수 있는 적응적 파이프라인 구조를 채택한 효율적인 영상 복호기 구조를 제안한다. 제안한 구조에서는 파라미터와 계수는 핸드셰이킹 방식으로 전용 신호선을 통해 전달되고 복호된 영상 데이터는 AMBA AHB 네트워크를 통해 메모리에 저장하거나 읽어 온다. 각 블록의 복호 처리 시간은 영상의 특성에 따라 가변적으로 변하고 각 연산기는 데이터가 준비되면 언제든지 동작을 할 수 있다. 제안한 구조에 따라 H.264 복호기를 설계하였고 FPGA를 이용하여 동작을 검증하였다.

• 한국경제지리학회지
• /
• 제25권3호
• /
• pp.339-356
• /
• 2022

본 연구는 창업과 기업 성장 기반이 취약한 비수도권 지역에서 지역대학의 우수한 연구·산학협력 역량을 기반으로 캠퍼스에 지역혁신생태계를 구축한 사례로서 일본의 홋카이도대학 리서치&비즈니스파크에 주목한다. 홋카이도대학 리서치&비즈니스파크는 캠퍼스 유휴부지를 활용하여 지역 주도로 중장기계획을 수립하고, 그에 따라 2003년부터 지금까지 점진적인 개발과정을 거쳐서 조성되고 있으며, 지역대학 특성화와 지역산업 기반을 고려한 바이오산업클러스터 구축이라는 산업적 접근 방식을 통해 산학협력 활성화를 추구하였다. 또한 지역 산학연관 협력적 거버넌스에 의해 다양한 기업지원 서비스를 제공한다. 이러한 홋카이도대학 리서치&비즈니스파크 조성전략은 최근 캠퍼스 혁신파크 등 대학 캠퍼스를 활용하여 지역의 발전을 도모하는 각종 정책 및 사업에 중요한 정책적 시사점을 제공한다.