• Journal of information and communication convergence engineering
• /
• 제16권2호
• /
• pp.125-129
• /
• 2018

In the field of computer graphics, rendering speed is one of the most important factors. Contemporary rendering is performed using 3D graphics systems with windowing system support. Since typical graphics systems, including OpenGL and the DirectX library, focus on the variety of graphics rendering features, the rendering process itself consists of many complicated operations. In contrast, early computer systems used direct manipulation of computer graphics hardware, and achieved simple and efficient graphics handling operations. We suggest an alternative method of accelerated 2D and 3D graphics output, based on directly accessing modern GPU hardware using the direct rendering manager (DRM) system. On the basis of this DRM support, we exchange the graphics instructions and graphics data directly, and achieve better performance than full 3D graphics systems. We present a prototype system for providing a set of simple 2D and 3D graphics primitives. Experimental results and their screen shots are included.

• 한국건설관리학회논문집
• /
• 제22권6호
• /
• pp.15-23
• /
• 2021

건설산업 혁신방안의 일환으로 건설생산체계가 개편됨에 따라 직접시공이 확대되고 있는 추세이다. 본 연구는 이러한 추세에 따라 직접시공 확대의 영향 및 문제점을 건축관련 업계의 입장과 외국 사례 조사를 통하여 분석하고 직접시공 확대 조치에 따른 영향을 다양한 측면에서 진단하여 직접시공의무제도를 바람직하게 적용하기 위한 대응방안을 제언하였다. 또한, 각 대안에 대하여 정책/행정 및 건축 분야 전문가 인터뷰를 통하여 효과 및 문제점을 평가하였다. 본 연구에서 도출된 직접시공의무제도 확대 및 효율화를 위한 대응방안은 발주자의 재량권 부여, 공사규모에 따른 차별화, 건설보증시스템 활용, 탄력적 작업반장제 도입의 4가지로, 전문가 인터뷰 결과 모두 직접시공 확대에 직간접적으로 긍정적 영향을 줄 것으로 평가되었다. 본 연구는 직접시공 현황을 조사하여 직접시공의무제도 적용에 있어 기초자료를 제공하며 또한 적절한 직접시공의무제도 적용을 위한 대응방안 도출과 이에 대한 전문가 평가를 통하여 직접시공 확대를 위한 방향을 제시함으로써 결과적으로 합리적 직접시공의무제도 운영을 통한 건설기업과 현장의 생산성 향상 및 효율화에 기여할 것으로 기대된다.

• 동력기계공학회지
• /
• 제20권2호
• /
• pp.32-42
• /
• 2016

Under part load condition of spark-ignition engine, pumping loss had great effect on engine efficiency. To reduce pumping loss, the study designed spark-ignited engines to make direct spray of gasoline to combustion chamber. In spark-ignited direct-injection engines, ignition probability is important for successful combustion and flame propagation characteristics are also different from pre-mixed combustion. This study designed a visualization testing device to study ignition probability of spark-ignited direct-injection LPG fuel and combustion flame characteristics. This visualization device consists of combustion chamber, fuel supply system, air supply system, electronic control system and data acquisition system. Ambient pressure, ambient temperature and ambient air flow velocity are important parameters on ignition probability of LPG-air mixture and flame propagation characteristics, and the study also found that sprayed LPG fuel can be directly ignited by spark-plug under proper ambient conditions. To all successful cases of ignition, the study recorded flame propagation image in digital method through ICCD camera and its flame propagation characteristics were analyzed.

• 전기학회논문지P
• /
• 제59권4호
• /
• pp.473-476
• /
• 2010

In this paper, we analyzed the short circuit current of a low voltage direct current distribution system. For the analysis, we performed the modeling of the low voltage direct current distribution system with a 6-pulse three-phase thyristor rectifier using the PSCAD/EMTDC, surveyed impedance of sources, transformers and distribution lines to run a simulation. A result of the simulation is that short circuit currents of the direct current distribution system with the rectifier decreased due to a thyristor-ON-resistance(Ron). But in case of the low thyristor-ON resistance, output fault current of the rectifier increased over three-phase short circuit current of an AC power system without a rectifier by regular ratio of the rectifier. Because the output fault current of the rectifier can increase over interrupting the capacity of circuit breakers, studying short circuit currents of a low voltage direct current distribution system with a rectifier is necessary for introducing the direct current distribution systems.

• Journal of Electrical Engineering and Technology
• /
• 제13권4호
• /
• pp.1450-1458
• /
• 2018

Commutation failures can deteriorate the availability of high-voltage direct current (HVDC) links and may lead to outage of the HVDC system. Most commutation failures are caused by voltage reduction due to ac system faults on inverter side. The commutation failure process can be divided into two stages. The first stage, from the occurrence to the clearing of faults, is called 'Deterioration Stage'. The second stage, from the faults clearing to restoring the power system stability, is called 'Recovery Stage'. Based on the analysis of the commutation failure process, this paper proposes a direct-current fuzzy controller including prevention and recovery controller. The prevention controller reduces the direct current to prevent Commutation failures in the 'Deterioration Stage' according to the variation of ac voltage. The recovery controller magnifies the direct current to speed up the recovery of power system in the 'Recovery Stage', based on the recovery of direct voltage. The validity of this proposed fuzzy controller is further proved by simulation with CIGRE HVDC benchmark model in PSCAD/EMTDC. The results show the commutation failures can be mitigated by the proposed direct-current fuzzy controller.

• 한국가금학회지
• /
• 제26권3호
• /
• pp.189-193
• /
• 1999

This experiment was conducted to investigate the effect of floor heating system on housing environment and performance in broiler production. PVC heating pipes(in 25cm spacing) were covered with concrete under the litter. Floor heating system was compared with conventional direct heating system. Each treatment had two replicates of 110 birds each. Litter moisture content was significantly reduced in floor heating system than conventional direct heating system(P〈0.05). Dust concentration was higher in floor heating system because of low litter moisture content. CO$_2$concentration was 2,900ppm and 1,500ppm on the direct heating system and floor heating system, respectively at the age of 1 week. Body weight was significantly higher in floor heating system at 7 weeks of age(P〈0.05). The results of the trial show that floor heating was useful heating system for broiler production.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2005년도 추계학술대회 논문집
• /
• pp.736-741
• /
• 2005

This paper presents electric characteristics analysis and safe configuration for extension power supply between existent 6.6kV ungrounded distribution system and establishment and improvement 22.9kV direct grounding distribution system. For this, we model 6.6kV ungrounded and 22.9kV direct grounding distribution system of urban underground, ground region. and rural electrical, unelectrical region using PSCAD/EMTDC and analyze voltage drop, charging current, ground and short fault through simulation. To analyze electric characteristics of extension power supply, we simulate extension power supply of overhead line of 6.6kV ungrounded system and underground line of 22.9kV direct grounding system of rural electrical region and propose operation condition for safe extension power supply through result of analysis. Characteristics of voltage drop, charging current, ground and short fault appear almost similarly with electrical characteristic of direct power supply. However, because unbalance of phases may cause relay's malfunction of ungrounded system and ground fault current of direct grounding system may demage facilities of ungrounded system, we propose safe system configuration such as impedance grounding system of neutral point.

• Journal of Power Electronics
• /
• 제9권3호
• /
• pp.491-498
• /
• 2009

The hydraulic-oil pump is widely used for building machinery, brake systems of vehicles and automatic control systems due to its high dynamic force and smooth linear force control performance. This paper presents a novel direct instantaneous pressure control of the hydraulic pump system with SRM drive. The proposed hydraulic pump system embeds the pressure controller and direct instantaneous torque controller. Due to the proportional relationship between pump pressure and torque, pressure can be controlled by the motor torque directly. The proposed direct torque controller can reduce inherent torque ripple of SRM, and develop a smooth torque, which can increase the stability of the hydraulic pump. The proposed hydraulic pump system has also fast step response and load response. The proposed hydraulic pump system is verified by computer simulation and experimental results.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2009년도 하계학술발표대회 논문집
• /
• pp.633-638
• /
• 2009

In this study the performance analysis and cooling capacity of desiccant cooling system incorporating regenerative cooler and direct evaporative cooler in the regeneration air inlet were investigated on the condition of low regeneration temperature and time rotation 180s and area ratio of regeneration to dehumidification section 0.7. The cooling capacity and COP are evaluated at various effectiveness values of the direct evaporative cooler or the regenerative evaporative cooler. As either of effectiveness of the regenerative and direct evaporative coolers of desiccant cooling system increases, both the cooling capacity and COP increase, but effectiveness value of regenerative cooler gives the opposite effect on the system performance. It is found that effectiveness of regenerative cooler less than 0.7 shows the optimum cooling capacity.

• 한국정밀공학회지
• /
• 제19권1호
• /
• pp.127-134
• /
• 2002

This study present a direct steering system using rack and pinion for ultra-small vehicles. The traditional small vehicles for special use had the limitation of space by reason of short wheel tread. These vehicles has adopted a indirect steering system or a center arm system for steering. The disadvantages of these system were deterioration of gear efficiency and increase of parts. For direct-linkage to both knuckles, steering system is made up of out-side tie rods, tie-rod ends, and gear box. Thus, the proposed system has a minimum number of parts. The experimental results show a maximum efficiency at minimum steering angle and a minimum clearance circle. These effects were accomplished by adopting a Ackerman-Jantaud theory.