• 한국경영과학회:학술대회논문집
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• 한국경영과학회/대한산업공학회 2003년도 춘계공동학술대회
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• pp.456-463
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• 2003

This paper presents a texture mapping method of a 3D scanned model with 2D images from different views. The texture mapping process consists of two steps Registration of the 3D facet model to the images by interactive points matching, and 3D texture mapping of the image pieces to the corresponding facets. In this paper. some implem entation issues and illustrative examples are described.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1994년도 춘계공동학술대회논문집; 창원대학교; 08월 09일 Apr. 1994
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• pp.556-556
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• 1994

• 한국정보과학회논문지:시스템및이론
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• 제30권5_6호
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• pp.299-306
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• 2003

본 논문에서는 내장형 실시간 시스템의 성능 개선을 위한 리엔지니어링(performance re-engineering) 기법을 제시한다. 시스템 리엔지니어링은 구현이 완료된 시스템에서 새로운 성능 요구사항을 만족시키기 위한 일련의 작업이라 할 수 있다. 일반적으로 실시간 시스템의 성능은 실시간 처리량(real-time throughput)과 입출력 시간 지연(input-to-output latency) 등으로 기술할 수 있으며 새로운 성능 요구사항은 이와 같은 파라미터를 통해 기술된다. 본 연구의 리엔지니어링 기법은 두 단계로 구성된다. 첫째, 시스템을 프로세스 네트워크의 형태로 파악한 후, 프로세스의 수행시간을 분석하여 병목(bottleneck)이 되는 프로세스를 찾아낸다. 둘째, 병목 프로세스의 수행시간을 개선한 수 있도록 프로세싱 요소의 성능비례계수(performance scaling factor)를 구한다. 성능비례계수는 성능 개선을 비율로 나타낸 것으로서 리엔지니어링 비용을 최소화하도록 그 값을 구한다. 따라서 유도된 성능비례계수에 따라 하드웨어 장치를 업그레이드하면 하드웨어 비용을 최적화할 수 있다. 이러한 방법을 사용하면 소프트웨어를 수정할 필요가 없으며, 리엔지니어링 비용 및 시간을 단축할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권1호
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• pp.146-170
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• 2017

Joint channel assignment and routing is a well-known problem in multi-radio wireless mesh networks for which optimal configurations is required to optimize the overall throughput and fairness. However, other objectives need to be considered in order to provide a high quality service to network users when it deployed with high traffic dynamic. In this paper, we propose a re-configuration optimization model that optimizes the network throughput in addition to reducing the disruption to the mesh clients' traffic due to the re-configuration process. In this multi-objective optimization model, four objective functions are proposed to be minimized namely maximum link-channel utilization, network average contention, channel re-assignment cost, and re-routing cost. The latter two objectives focus on reducing the re-configuration overhead. This is to reduce the amount of disrupted traffic due to the channel switching and path re-routing resulted from applying the new configuration. In order to adapt to traffic dynamics in the network which might be caused by many factors i.e. users' mobility, a centralized heuristic re-configuration algorithm called State-Aware Joint Routing and Channel Assignment (SA-JRCA) is proposed in this research based on our re-configuration model. The proposed algorithm re-assigns channels to radios and re-configures flows' routes with aim of achieving a tradeoff between maximizing the network throughput and minimizing the re-configuration overhead. The ns-2 simulator is used as simulation tool and various metrics are evaluated. These metrics include channel-link utilization, channel re-assignment cost, re-routing cost, throughput, and delay. Simulation results show the good performance of SA-JRCA in term of packet delivery ratio, aggregated throughput and re-configuration overhead. It also shows higher stability to the traffic variation in comparison with other compared algorithms which suffer from performance degradation when high traffic dynamics is applied.

• 한국기계가공학회지
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• 제14권6호
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• pp.98-103
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• 2015

Swing reducers are widely used in special vehicles that have swing motions. Generally, compact swing reducers were constituted by a worm gear pair. Worm gears are one of the most important technical devices for transmitting torque between spatially crossed axes. Due to their high transmission ratio and compact structure, they are widely used in power transmission applications where high reduction is required. This paper presented approaches to improve the transmission efficiency and assembling performance of 3.5 ton class worm gear swing reducers. Worm wheel and the case of swing reducers were optimized and certified by a finite element method. Finally, an actual swing reducer was processed and assembled to test the performance.

• 제어로봇시스템학회논문지
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• 제21권5호
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• pp.427-433
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• 2015

Hot forging industry workers are prone to encounter several health risks due to lack of automation and poor working environment conditions. These workers particularly suffer from muscle fatigue owing to the constant handling of heavy products during the forging process. Thus we developed an assistant robot for workers who carry out hot forging tasks. The purpose of a robot is to compensate gravity-loads for heavy products. To verify the functionality of a robot, we performed a muscle fatigue analysis using Electromyography (EMG) signals. Four muscles of the upper extremity were chosen to measure muscle activity. And experiment conditions were setup to imitate the hot forging process. Post experimental analysis of the captured muscle activity revealed a reduction in the median frequency of the EMG signals, which means clear fatigue reduction due to a robot's assistance. The developed assist robot with compact and economical components can be efficiently utilized at forging work sites to create better working conditions for operators.

• 한국기계가공학회지
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• 제16권6호
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• pp.153-158
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• 2017

Reducer is a device to transmit and change torque and speed from drive shaft to driven shaft with excellent transmission efficiency, and it is widely used in many areas today. Reduction gear consists of two axes, gear, bearing supporting axes, and housing. The simplest method to transmit rotation or power to multiple axes is to attach circular plates to two axes and contact each other. However, in this case, if increasing number of rotations or if contact pressure is small, because of slipping, it cannot transmit power. For problems for the current reducer case, it is heavy and its assembling and repair is difficult. In addition, there are few studies about manufacturing and performance testing of worm gear reducer, causing lack of the foundation to improve the product competition and the performance.

• 한국입자에어로졸학회지
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• 제18권4호
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• pp.97-107
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• 2022

The geometry of popular wave plate type mist eliminator for the wet flue gas desulfurization process was improved, fabricated, and experimentally evaluated. A Mist eliminator is a type of inertial particle collector which collection efficiency is proportional to the velocity of the gas phase. However, as the amount of re-entrainment is also proportional to the gas phase velocity, there is a limitation for the gas phase flow rate. Re-entrainment is one of the most important issues in a mist eliminator and is likely to occur as the input of the liquid phase and flow rate of the gas phase increase. In order to resolve this problem, the projection angle of the improved mist eliminator is set to 30° from the conventional one while maintaining the cross-section. With low flow rate conditions, the modified mist eliminator showed a similar pressure drop and overall collection efficiency. However, with conditions in which re-entrainment is obviously occurring, the modified mist eliminator showed better performance in draining droplets than the conventional one. As a result, the modified mist eliminator showed higher overall collection efficiency.

• 콘크리트학회논문집
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• 제25권1호
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• pp.53-61
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• 2013

코일철근의 직선화 가공성을 향상시키기 위한 마디 형상으로, 철근 축과 마디 사이각 $50^{\circ}$, 마디 윗면 폭(crest width) $0.15d_b$, 마디의 종단면 각도(flank inclination) $55^{\circ}$에 초승달 모양 지압면을 가진 생선뼈 마디(fishbone-shaped transverse rib)를 제안하였다. 이 형상은 직선화 기계의 롤러 홈(groove)과 철근 외부의 접촉면적을 넓혀 마디 손상을 최소화하며 직선도를 향상시키고 가공 생산성을 높일 것으로 기대된다. 제안된 형상을 포함하여 마디 각도가 상이한 3종류의 코일철근(SD500D16 강종)에 대한 부착강도 평가를 위해 겹침이음실험을 실시하였다. 3종의 코일철근은 기존 부착강도 평가식에 따른 예측값보다 평균 10%이상 높은 부착강도를 지닌 것으로 평가되었다. 이것은 코일철근의 상대마디면적비가 기존 평가식 유도에 사용된 실험보다 높기 때문으로 판단된다. 부착강도에 대한 직선철근과 코일철근의 상관계수(correlation coefficient)는 0.94이상 이였으며, 코일철근의 부착성능이 직선철근과 거의 유사함을 알 수 있다. 따라서 실험에 사용된 코일철근의 정착길이와 이음길이 설계에 현행설계기준을 적용하는 것이 타당한 것으로 평가된다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.568-571
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• 2008

The computation of moving interface by the level set method typically requires reinitializations of level set function. An inaccurate estimation of level set function ${\phi}$ results in incorrect free-surface capturing and thus errors such as mass gain/loss. Therefore, accurate and robust reinitialization process is essential to the free-surface flows. In the present paper, we pursue further development of the reinitialization process, which evaluates directly level set function ${\phi}$ using a normal vector in the interface without solving the re-distancing equation of hyperbolic type. The Taylor-Galerkin approximation and P1P1splitting FEM are adopted to discretize advection equation of the level set function and the Navier-Stokes equation, respectively. Advection equation of free surface and re-initialization process are validated with benchmark problems, i.e., a broken dam flow and time-reversed single vortex flow. The simulation results are in good agreement with the existing results.