• Proceedings of the KIEE Conference
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• summer
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• pp.923-925
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• 2004

A lot of conventional automotive components driven by mechanical power source are being replaced with electrical ones to comply with the demands of market and customer, therefore the amount of electric energy used in a vehicle will be increased continuously. The increment of electric power demand causes interest on new higher power system such as 42V Power Net, and furthermore necessity for development of energy storage device is highlighted recently. This paper present the design of the BLDC motor for electric air-conditioner in 42V system and compare with the characteristics of several type BLDC motor.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.208-210
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• 2005

A lot of conventional automotive components driven by mechanical power source are being replated with electrical ones to comply with the demands of market and customer, therefore the amount of electric energy used in a vehicle will be increased continuously. The increment of electric power demand causes interest on new higher power system such as 42V Power Net, and furthermore necessity for development of energy storage device is highlighted recently. This paper presents the design of the BLDC motor drive for Cooling Fan in 42V automotive system. Test results confirmed the feasibility of the proposed motor drive system design.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2022.06a
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• pp.1203-1206
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• 2022

자율주행, IoT 등 많은 양의 영상 정보를 실시간으로 처리해야 하는 기술과 mobile device 등의 기기에서 Machine Learning 연산을 하는 소프트웨어들이 등장함에 따라 사람을 위한 영상을 출력하는 영상 부호화 기술 대신 기계의 vision task 성능을 위해 특화된 영상 부호화 기술의 필요성이 대두됐다. 본 연구에서는 영상에서 추출한 특징맵을 Neural-Net based Video Coding 모델을 이용해 압축률과 기계의 vision task 성능을 동시에 최적화한다. 또한, 하드웨어 친화적인 block-based 처리와 이로 인한 성능 저하를 최소화하기 위해 적응적 resizing 방식을 제안한다.

• Nuclear Engineering and Technology
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• v.55 no.5
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• pp.1559-1566
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• 2023

This study developed a quasi-monoenergetic neutron source (QMN) for the semiconductor device's soft error rate test (SER). Quasi-monoenergetic neutrons are generated by ⁹Be(p, n)⁹B nuclear reaction with a 1 mm beryllium target and 30 MeV protons from a cyclotron. An 8 mm water in the back of the beryllium target is used for avoiding proton penetration. The neutron spectra simulated by MCNP showed that the peak energy was around 26.5 MeV. The heat flow and mechanical properties are numerically analyzed, and the safe operating conditions are therefore determined.

• Nuclear Engineering and Technology
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• v.56 no.2
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• pp.437-443
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• 2024

The development and testing of inspection equipment is necessary for the safe deployment of advanced nuclear reactors. One proposed advanced reactor design is Westinghouse's lead-cooled fast reactor (LFR). In this paper, the process of achieving adequate wetting for an ultrasonic under-lead viewing system is discussed and results presented. Such a device would be used for inspection in the molten lead core during reactor outages. Wider tests into the wetting of various materials in molten lead at microscale were performed using electron microscopy. The possible mechanisms and kinetics for materials wetting in lead, particularly stainless steel and nickel, are proposed and discussed.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.289-300
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• 2010

Recently, diverse information which are location, call history, SMS history, photographs, and video can be collected constantly from mobile devices such as cellular phone, smart phone, and PDA. There are many researchers who study services for searching and abstraction of personal daily life with contextual information in mobile environment. In this paper, we introduce MyLifeBrowser which is developed in our previous work. Also, we explain LPS and correction of GPS coordinates as extensions of previous work and show LPS performance test and evaluate the performance of expanded keywords. MyLifeBrowser which provides searching personal information in mobile device and support of detecting related information according to a fragmentary keyword and common knowledge in ConceptNet. It supports the functionality of searching related locations using Bayesian network that is designed by the authors. In our experiment, we visualize real data through MyLifeBrowser and show the feasibility of LPS server and expanded keywords using both Bayesian network and ConceptNet.

• Journal of Mechanical Science and Technology
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• v.19 no.5
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• pp.1158-1168
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• 2005

A shunt from the left ventricle to the left anterior descending artery is being developed for coronary artery occlusive disease, in which the shunt or conduit connects the the left ventricle (LV) with the diseased artery directly at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Computational fluid dynamic analysis for the shunt hemodynamics was also done using a commercial finite element package. Simulation results indicate that in complete left anterior descending artery (LAD) occlusion, flow can be returned to approximately 65% of normal, if the conduit resistance is equal for forward and reverse flow. The net coronary flow can increase to 80% when the backflow resistance is infinite. The increases in flow rate produced by asymmetric flow resistance are enhanced considerably for a partial LAD obstruction, since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but considerably augments it when the resistance is asymmetric. The computational results suggest that an LV-LAD conduit will be beneficial when the resistance due to artery stenosis exceeds 27 PRU, if the resistance is symmetric. Fluid dynamic simulations for the shunt flow show that a recirculating region generated near the junction of the coronary artery with the bypass shunt. The secondary flow is induced at the cutting plane perpendicular to the axis direction and it is in the attenuated of coronary artery.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.391-394
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• 2002

There has recently been much interest and research in developing digital x-ray systems based on using amorphous selenium(a-Se) photoconductors as the image receptor. The amorphous selenium layer that is currently being studied for use as an x-ray photoconductor is not pure a-Se but rather amorphous selenium alloyed with arsenic. We fabricated samples using the selenium and arsenic alloy with various concentrations of the arsenic. In this work, x-ray photoconductor using amorphous selenium alloyed with arsenic were fabricated with different concentrations of the arsenic (0.1 wt.%, 0.3wt.%, 0.5wt.%, 1wt.%, 1.5wt.%, 3wt.%, 5wt.%). The seven kind of samples was fabricated with a-Se alloyed with arsenic through vacuum thermal evaporation. We also investigate the arsenic concentration dependence on the device performance in radiation detector. The electric characteristics of radiation detector devices with changing additive ratio of the arsenic is performed by measuring the x-ray induced photocurrent and integrating it over time to find the total charge. The thickness of a-Se is $100{\mu}m$. Bias voltages $3V/{\mu}m$, $6V/{\mu}m$， $9V/{\mu}m$ are applied at the samples. As results, the net charge of a-Se 0.3% As sample is $526.0pC/mR/cm^2$ at $9V/{\mu}m$ bias. The net charge is decreased as with the increasing additive ratio of arsenic.

• The KIPS Transactions:PartD
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• v.19D no.4
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• pp.281-292
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• 2012

A wide variety of smartphone applications is increasing the usage time of smartphone. Due to the increased time, it becomes difficult to providing stable services to users with limited battery capacity. The past works have been performed the power management of mobile device toward long-lasting battery development or low-power electric devices. However as the complexity of software embedded into system are increased, the research interests of the software power analysis is also increased. Among these studies on the software power analysis, model-based analysis technique is one of major interests because it can be able to analyze the power consumption before the development of source codes, then the analysis result can be used in the development of the software system, This paper suggests a model-based power analysis technique using UML state machine diagram. Our proposed technique estimates the power consumption by the simulation of Perti-net which is transformed from the state machine diagram.

• The KIPS Transactions:PartA
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• v.16A no.5
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• pp.339-346
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• 2009

In order to connect web services, clients generally should use heavy frameworks such as .Net framework and Java run-time environment, which require high performance hardware resources like a personal computer. Therefore, it is impossible for sensor nodes to handle web services due to their limited resources. In this paper, a client agent framework is proposed for dynamically connecting web services in the client node with limited resources. A client agent, which is managed by the framework in other server, has full capability for connecting web services, while a real client has a simple connection module with the client agent. In this framework, a client agent is dynamically generated using the WSDL in the web service server. By using the framework, sensor nodes or mobile devices can enhance their functionalities and services by accessing web services with minimum resources.