• 한국생산제조학회지
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• 제22권4호
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• pp.708-716
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• 2013

This study aims to understand the applied forces and related vibrational characteristics of a tripod joint (TJ), which is mostly used in front-drive-type middle-sized sedans in South Korea. The plunging force (PF) and generated axial force (GAF) are the most influential quantities related to the vibrational characteristics of a driveshaft. To obtain meaningful data, specially designed tests were performed using MTS test sets. The results of direct measurements reveal that higher PF and GAF values appear to worsen the vibrational characteristics of the vehicle. On the other hand, the measured apparent mass is useful for calculating the applied forces for a short driveshaft that has no dynamic vibration absorber. Among diversely controlled samples, it shows that the viscosity and tight fit are very sensitive to shudder vibrations of the vehicle. Therefore, these are good design factors for quality controls in the production line of constant-velocity joints.

• 한국생산제조학회지
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• 제26권1호
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• pp.36-43
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• 2017

A drug infuser is a well-known device that is widely used in various areas of clinical practice. However, some materials used in the drug infuser have been developed for particular purposes and thus, their design characteristics have to be changed considerably. Especially, the implications of a new filler in the drug infuser have migrated to the areas of body corrections in plastic surgery. In this study, the design process of a drug infuser managing a large content volume has been studied from the perspective of structure safety. A new design of the drug infuser that uses a 10 cc filler with high viscosity is presented. Finite element analysis is used to confirm that the assembled drug infuser is safe enough to hold the required loading of 490 N. Furthermore, the final prototype of the drug infuser was successful in reducing the weight up to 400 g without compromising the safety.

• 혜화의학회지
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• 제18권2호
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• pp.95-104
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• 2009

This study was carried out through the investigation of Oriental and Western medical literature and we was discovered these conclusions about the etiology, treatment, prescription of habitual abortion. The result of this study were as follows : 1. The habitual abortion does agree with 'Hwaltae(滑胎)' and means that spontaneous abortion repeats three times or more. 2. The etiology of habitual abortion is divided 'Deficiency of kidney'(腎虛), 'Deficiency of vital energy and blood'(氣血虛弱), 'Deficiency of yin'(陰虛), 'Clotted blood'(瘀血). 3. By means of cause, the treatment of habitual abortion was mainly made use of 'Tonifying kidney and promoting spleen'(補腎健脾), 'Invigorating vital energy and nourishing blood'(補氣補血), 'Supplementing yin fluid and alleviating fever'(滋陰淸熱), 'Resuscitating blood and removing clotted blood'(活血祛瘀). 4. By means of cause, the prescription of habitual abortion was frequent made use of Bosingochunghwan(補腎固沖丸), Bosingotae$\breve{u}$m(補腎固胎飮), Taesanbans$\breve{o}$ksan(泰山磐石散), $Ch\breve{o}ng\breve{u}mboinghwan$(千金保孕丸), Agyotang(阿膠湯), Gungguibojungtang(芎歸補中湯), Taewon$\breve{u}$m(胎元飮), Gotaej$\breve{o}$n(固胎煎), Baekchulj$\breve{o}$n(白朮煎), Sas$\breve{o}$ngsan(四聖散), Gyegibokryonghwan(桂枝茯苓丸), $Dangguich\breve{o}ng\breve{u}mtang$(當歸千金湯). 5. The Western medical etiology of habitual abortion(recurrent spontaneous early pregnancy loss) is divided Genetic factor(Chromosome aberration), Anatomical deformity, Endocrinologic disorder, Infection, Immunologic factor, Unknown factor(Others).

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.429-430
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• 2011

This paper presents a simple and cost-effective stand-alone rapid battery charging system of 30kW for electric vehicles. The proposed system mainly consists of active front-end rectifier of neutral point clamped 3-level type and non-isolated bi-directional dc-dc converter of multi-phase interleaved half-bridge topology with coupled inductors. The charging system is designed to operate for both lithium-polymer and lithium-ion batteries. The complete charging sequence is made up of three sub-interval operating modes; pre-charging mode, constant-current mode, and constant-voltage mode. The pre-charging mode employs the staircase shaped current profile to accomplish shorter charging time while maintaining the reliable operation of the battery. The proposed system is able to reach the full-charge state within less than 16min for the battery capacity of 8kWh by supplying the charging current of 67A. The optimal discharging algorithm for Vehicle to the Grid (V2G) operation has been adopted to maintain the discharging current of 1C. Owing to the simple and compact power conversion scheme, the proposed solution has superior module-friendly mechanical structure which is absolutely required to realize flexible power expansion capability in a very high-current rapid charging system.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.178.2-178.2
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• 2011

바이오디젤이란 식물성 기름, 동물성 지방, 폐식용유 등의 재생 가능한 자원을 촉매 존재 하에 알코올과 반응시켜 생성되는 에스테르 혼합물을 말하며 경유와 물성이 유사하므로 경유에 혼합하여 압축착화 방식인 디젤엔진에 사용할 수 있다. 그러나 바이오디젤은 경유에 비하여 탄소-탄소 간 이중결합을 가지고 있는 성분을 많이 함유하고 있기 때문에 공기에 의해 산화가 일어나기 쉽다. 일반적으로 폐놀계 향산화제인 t-buthylhydroquinone(TBHQ)를 사용하여 산화안정성을 향상시키나 국내에서 사용되는 산화방지제는 전량 수입에 의존하고 있어 제품 개발에 의한 국산화가 시급한 실정이다. 본 연구에서는 폐유지로부터 생산한 바이오디젤의 산화안정성 향상을 위하여 폐놀 및 아민계 등의 산화방지제를 합성하여 바이오디젤에 적용하였으며, 다양한 물성시험방법을 적용하여 석유 및 석유대체연료 사업법에서 규정하는 바이오디젤의 품질기준을 확인하였다. 또한 EN 14112 바이오디젤 산화안정성 시험방법으로 폐놀 및 아민계 등의 산화안정성을 확인하였다. 본 연구는 산학연 공동기술개발 1차년도 사업으로 한국화학연구원과 공동으로 수행하였으며, 산화방지제 적용평가를 통해 우수한 제품을 선정하여 2차년도에는 차량 테스트를 통해 연료 첨가제로서의 적합성을 검증할 예정이다.

• 로봇학회논문지
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• 제15권2호
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• pp.197-204
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• 2020

In this paper, we present a learning platform for robotic grasping in real world, in which actor-critic deep reinforcement learning is employed to directly learn the grasping skill from raw image pixels and rarely observed rewards. This is a challenging task because existing algorithms based on deep reinforcement learning require an extensive number of training data or massive computational cost so that they cannot be affordable in real world settings. To address this problems, the proposed learning platform basically consists of two training phases; a learning phase in simulator and subsequent learning in real world. Here, main processing blocks in the platform are extraction of latent vector based on state representation learning and disentanglement of a raw image, generation of adapted synthetic image using generative adversarial networks, and object detection and arm segmentation for the disentanglement. We demonstrate the effectiveness of this approach in a real environment.

• 한국물환경학회지
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• 제25권5호
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• pp.758-763
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• 2009

This study presents the optimal conditions of zero-valent iron (ZVI) pretreatment for color removal from real dye wastewater. Removal of color by ZVI was strongly subject to the acidity of the wastewater buffering the pH increased after ZVI reduction. The real dye wastewater did not contain a sufficient amount of acidity and thus it was necessary to supplement acid to the dye wastewater before treatment. In continuous operation of iron column, the empty bed contact time (EBCT) and initial pH were varied to find the optimal conditions. A non-linear regression model fitted well the experimental result predicting that the optimal EBCT and pH for 80% removal efficiency was present in the range of 57~90 and 5~5.9, respectively. Color of column effluents could be further removed in the following biological oxidation step and the biodegradability of wastewater was also enhanced after iron pretreatment.

• Journal of Computational Design and Engineering
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• 제2권1호
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• pp.67-72
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• 2015

Recently, along with the improvements of geometry modeling methods using sketch-based interface, there have been a lot of developments in research about generating surface model from 3D curves. However, surfacing a 3D curve network remains an ambiguous problem due to the lack of geometric information. In this paper, we propose a new algorithm for estimating the normal vectors of the 3D curves which accord closely with user intent. Bending energy is defined by utilizing RMF(Rotation-Minimizing Frame) of 3D curve, and we estimated this minimal energy frame as the one that accords design intent. The proposed algorithm is demonstrated with surface model creation of various curve networks. The algorithm of estimating geometric information in 3D curves which is proposed in this paper can be utilized to extract new information in the sketch-based modeling process. Also, a new framework of 3D modeling can be expected through the fusion between curve network and surface creating algorithm.

• Korea-Australia Rheology Journal
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• 제16권2호
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• pp.75-83
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• 2004

The purpose of the present study is to investigate fluid mechanical interactions between two major abdominal aortic branches under both steady and pulsatile flow conditions. Two model branching systems are considered: two branches emerging off the same side of the aorta (model 1) and two branches emerging off the opposite sides of the aorta (model 2). At higher Reynolds numbers, the velocity profiles within the branches in model 1 are M-shaped due to the strong skewness, while the loss of momentum in model 2 due to turning effects at the first branch leads to the absence of a reversed flow region at the entrance of the second branch. The wall shear stresses are considerably higher along the anterior wall of the abdominal aorta than along the posterior wall, opposite the celiac-superior mesenteric arteries. The wall shear stresses are higher in the immediate vicinity of the daughter branches. The peak wall shear stress in model 2 is considerably lower than that in the model 1. Although quantitative comparisons of our results with the physiological data have not been possible, our results provide useful information for the localization of early atherosclerotic lesions.

• 한국생산제조학회지
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• 제26권3호
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• pp.320-327
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• 2017

The main function of an infuser is to ensure constant dosage of a drug. Elastomer drug infusers have been used widely owing to their economic advantages. The mechanism of the device is primarily based on the pressure created from the elastic material that contains the drugs. However, as the drug is infused and the internal pressure is reduced, the drug is not linearly infused at all times. This study involves investigating factors to improve the design of the infuser. The first factor is the range of proper deformation, which does not affect a significant amount of stress variation during infusion. The second is concerned with the flow restrictor and the associated design variables are recommended by employing finite element analysis and the factorial experiment technique. The last factor is related to the spring device connected to balloon. The results showed that the drug reservoir can compensate for unexpected pressure gradient drops.