• Journal of Advanced Marine Engineering and Technology
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• v.30 no.2
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• pp.225-230
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• 2006

This study investigates drying condition when a small fan is added to a operating the free-breathing proton exchange membrane fuel cells (PEMFCs) with dry $H_2$ and Air. Polarization tests were conducted on PEMFCs at cell temperatures between 30 and $50^{\circ}C$ under dry operation. In the results, the cell performance strongly depended on the cell temperature and the cathode gas stoichiometric flow rates. The cell performance increases as cell temperature decreases from 50 to $30^{\circ}C$. In the domain where the stoichiometry of air is quite large, reduction of the concentration overpotential compensated the increased internal resistance due to drying. The maximum performance was obtained at the small air flow rate beyond which flooding occurs. This indicates that the fan should be operated in the stoichiometry domain with a well designed cell structure to avoid flooding.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.4
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• pp.31-43
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• 2019

Take-overs occur in autonomous vehicles at levels 3 and 4 based on SAE. For safe take-over, it is necessary to set the time required for diverse drivers to complete take-over in various road conditions. In this study, take-over time and stabilization characteristics were measured to secure safety of take-over in autonomous vehicle. To this end, a virtual driving simulator was used to set up situations similar to those on real expressways. Fifty drivers with various sexes and ages participated in the experiment where changes in traffic volume and geometry were applied to measure change in takeover time and stabilization characteristics according to various road conditions. Experimental results show that the average take-over time was 2.3 seconds and the standard deviation was 0.1 second. As a result of analysis of stabilization characteristics, there was no difference in take-over stabilization time due to the difference of traffic volume, and there was a significant difference by curvature changes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.22 no.6
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• pp.246-263
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• 2023

The stabilization time of take-over refers to the time it takes for driving to stabilize after the take-over. Following a take-over request from an automated driving system, the driver must become aware of the road driving environment and perform manual driving, making it crucial to clearly understand the relationship between the driving environment and stabilization time of take-over. However, previous studies specifically focusing on stabilization time after take-over are rare, and research considering the driving environment is also lacking. To address this, our study conducted experiments using a driving simulator to observe take-over transitions. The results were analyzed using a liner mixed model to quantitatively identify the driving environment factors affecting the stabilization time of take-over. Additionally, coefficients for stabilization time based on each influencing factor were derived.

• Nuclear Engineering and Technology
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• v.27 no.2
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• pp.216-225
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• 1995

Simulation for a dynamic analysis of the electrolytic preparation of U(IV) in two-phases system, which consisted of mass transfer of U(VI) from TBP phase into HNO$_3$ solution and electrolytic re-duction of U(VI) to U(IV) at a cathode in aqueous phase, was carried out in order to establish the most suitable operating condition and best electrode area as basic design data for the system. It was found that maintaining an appropriate mass transfer rate was more significant rather than enlarging the surface area of the cathode for more effective production yield of U(IV). The electrode area and the operation time affected deeply the production composition of U(IV) in the resulting aqueous phase. And optimal electrode areas ore evaluated to meet production criteria of U(IV) of resulting solution in several system conditions. Though about 0.37M HNO$_3$ was preferable to prepare the solution of U(IV), nitric acid concentration should be higher than 0.5M to prevent a hydrolysis of U(IV) in the aqueous phase.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.3
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• pp.503-512
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• 2020

The products using blowers include hand dryers, automatic car washers, dryers, and vacuum cleaners. The features of these products require a structure and control algorithm so that a strong wind is blown out at the moment. Electric motors according to the existing excitation method include a direct winding type, a decentralized type, a lottery type, and a permanent magnet type. Conventional electric motors have a disadvantage when the starting current is large during high-speed rotation and the number of rotations is irregular. In order to improve this, research on high-speed BLDC motor control has designed 800W-class high-speed BLDC motor control and circuit through driving circuit design, sensorless control algorithm, simulation, experiment, etc., and more than 95% high efficiency evaluation method of driving performance of controller, prototype experiments and verification were studied.

• Journal of the HCI Society of Korea
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• v.14 no.2
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• pp.49-60
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• 2019

With the appearance of self-driving cars and electric cars, the automobile industry is rapidly changing. In the midst of these changes, HMI studies are becoming more important as to how the driver obtains safety and convenience with controlling the vehicle. This study sought to understand how automobile manufacturers understand the driving situation, and how they define and limit driver interaction. For this, prior studies about HMI were reviewed and 15 participants performed an on-road study to drive vehicles from five manufacturers with using their interfaces. The results of the study confirmed that buttons and switches that are easily controlled by the user while driving were different from manufacturer to manufacturer. And there are some buttons that are more intensively controlled and others that are difficult to control while driving. It was able to derive 'selection and concentration' from Audi's vehicle, 'optimization of the driving ' from BMW's, 'simple and minimize' from Benz's vehicle, 'remove the manual distraction' from the vehicle of Lexus, and 'visual stability' from KIA's vehicle as the distinctive keywords for the HMI. This shows that each manufacturer has a different definition and interpretation of the driver's driving control area. This study has a distinct value in that it has identified the characteristics of vehicle-specific HMI in actual driving conditions, which is not apparent in appearance. It is expected that this research approach can be useful to see differences in interaction through actual driving despite changes in driving environment such as vehicle platooning and self-driving technology.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.224-227
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• 2015

Data transmission via the car driver's tethered smart phone may have a volume-dependent billing in case car driver' phone transmits data in real-time to the remote data center. The on-board diagnosis data generated are temporary stored locally to mobile remote diagnosis application on the car driver's phone, and then transmit to the data center later when car driver connects to the Internet. To increase the easiest of using the remote vehicle application without blocking other tasks to be executing on the cloud, node.js stands as a suitable candidate for handling tasks of data storage on the cloud via mobile network. We demonstrate the effectiveness of the proposed architecture by simulating a preliminary case study of an android application responsible of real time analysis by using a vehicle-to- smart phones applications interface approach that considers the smart phones to act as a remote user which passes driver inputs and delivers output from external applications. In this paper, we propose a study on development of Remote Vehicle fault diagnostic system features web server architecture based event loop approach using node.js platform, and wireless communication to handle vehicle diagnostics data to a data center.

• Polymer(Korea)
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• v.29 no.1
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• pp.48-53
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• 2005

Tire wear is one of the factors that most drivers have concerned and is closely related to the tire life. It is very difficult to predict tire wear because the factors affecting tire wear seem to be very comlicated. Tire wear test should be performed at real conditions for the evaluation of tire wear. In this study, we analyze tire wear according to the severities of test courses by using the dedicated test method, more severe than real driving conditions. In order to simplify the factors affecting tire wear, we define roads’ driving severities to be driving severity numbers, DSNs which are obtained by measuring the lateral accelerations of test courses. And we compared tire wear rates and profiles with DSNs. These test results can provide the tire design guide to meet tire wear performance.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2000.11a
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• pp.59-59
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• 2000

원자력발전소 1차계통과 격납용기 내부에서 사용되는 주요 부품들은 운전중에 발생한 방사 성 물질들의 침투와 홉착에 의해 오염되어 간다. 이 오염된 부품 및 장비, 공구, 방호복, 방호모자, 작업화 등의 세정과 정비를 위해서는 제염이 선행되어야 한다. 현재의 제염법은 2차 방사성 폐기물을 발생하는 문제점이 있다. 따라서I 2차 폐기물의 발생을 근원적으로 줄일 수 있는 새로운 제염방안이 절실히 요구되고 있는 실정이다. 본 논문에서는 이러한 문제점을 해결할 수 있는 제염법을 개발하기 위해 2가지 방법을 적용하였다. 첫째로, 원자력 발전소에 서 나오는 방사능 오염 세탁물 제염을 위한 액체 및 초임계 이산화탄소를 이용한 방사능 오염물 제염기를 개발하였다. 제염기는 반응기(16 liteer), 회수시스템 그리고 저장용기로 구성되어있다. 세정에 사용된 모든 이산화탄소는 회수되어 재사용 되어지므로 2차 폐기물의 발생을 근원적으로 없앨 수 있다. 제염성능실험결과 제염지수가 목표치보다는 낮았다. 이는 제염 기에 계면활성제와 기계적인 힘을 가한다면 높은 제염지수를 얻을 수 있을 것으로 예상된다. 둘째로, 발전소에서 나오는 오염된 공구나 장비의 세척을 위한 가변형 노즐 드라이 아이스 세척 장치를 개발하였다. 표면세정시 얼음층 형성방지를 위하여 열공급장치를 부착하였다. 유라표면에 지문을 묻혀 실험한 결과 쉽게 제거되었다. 실제 발전소에 있는 P Pump-housing의 표면을 실험한 결과 방사능의 약 40-80%가 제거되었다. 이 장치는 검출기, 제어장치, 용액상에서 세척될 수 없는 장치에 적용할 수 있는 효율적인 세척법이다. 이는 프리프레그의 표면처리 가 충과 충간의 접착강도를 증가시키고 또한 탄소섬유와 에폭시 간의 계면력을 증가시킨데 기인하는 것으로 사려된다.되었으며, duty-on 시간의 증가에 따라 $Cr_2N$ 상의 형성이 점점 많아져 80% duty-on 시간 경우에는 거의 CrN과 $Cr_2N$ 상이 공존하는 것으로 나타났다. 또한 duty-on 시간이 증가할수록 회절피크의 세기가 증가하여 결정화가 더 많이 진행되어짐을 알 수 있었다. 마찬가지로 바이어스 펄스이 주파수에 다른 결정성의 변화도 펄스의 주파수가 증가할수록 박막이 결정성이 좋아지고 $Cr_2N$ 상이 쉽게 형성되었다. 증착 진공도에 따른 결정성은 상대적으로 질소의 농도가 높은 낮은 진공도에서는 CrN 상이 주로 형성되었으며, 반대로 높은 진공도에서는 $Cr_2N$ 상이 많이 만들어졌다. 즉 $1.3{\times}10^{-2}Torr$의 증착 진공도에서는 CrN 상만이 보이는 반면 $9.0{\tiems}1-^{-2}Torr$ 진공도에서부터 $Cr_2N$ 상이 형성되기 시작하여 $5.0{\tiems}10^{-2}Torr$ 진공도에서는 두개의 상이 혼재되어 있음을 알 수 있었다. 박막의 내마모성을 조사한 결과 CrN 박막의 마찰 계수는 초기에 급격하게 증가한 후 0.5에서 0.6 사이의 값으로 큰 변화를 보이지 않았으며, $Cr_2N$ 박막도 비슷한 거동을 보였다.차 이, 목적의 차이, 그리고

• KEPCO Journal on Electric Power and Energy
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• v.5 no.3
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• pp.209-213
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• 2019

Recently, demand for high energy density and long cycling stability of energy storage system has increased for application using with frequency regulation (F/R) in power grid. Supercapacitor have long lifetime and high charge and discharge rate, it is very adaptable to apply a frequency regulation in power grid. Supercapacitor can complement batteries to reduce the size and installation of batteries. Because their utilization in a system can potentially eliminate the need for short-term frequent replacement as required by batteries, hence, saving the resources invested in the upkeep of the whole system or extension of lifecycle of batteries in the long run of power grid. However, low energy density in supercapacitor is critical weakness to utilization for huge energy storage system of power grid. So, it is still far from being able to replace batteries and struggle in meeting the demand for a high energy density. But, today, LIC (Lithium Ion Capacitor) considered as an attractive structure to improve energy density much more than EDLC (Electric double layer capacitor) because LIC has high voltage range up to 3.8 V. But, many aspects of the electrochemical performance of LIC still need to be examined closely in order to apply for commercial use. In this study, in order to improve the capacitance of LIC related with energy density, we designed new method of pre-doping in anode electrode. The electrode in cathode were fabricated in dry room which has a relative humidity under 0.1% and constant electrode thickness over $100{\mu}m$ was manufactured for stable mechanical strength and anode doping. To minimize of contact resistance, fabricated electrode was conducted hot compression process from room temperature to $65^{\circ}C$. We designed various pre-doping method for LIC structure and analyzing the doping mechanism issues. Finally, we suggest new pre-doping method to improve the capacitance and electrochemical stability for LIC.