• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.407-408
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• 2006

Almost all injection molds have multi-cavity, which are designed with geometrically balanced runner system in order to made filling balance between cavity to cavity during injection molding. However, filling imbalance has been existed in the geometrically balanced runner system. In this study, we made an experiment and surveyed that are filling balanced variation according to molding condition with thermoplastic vulcanizate (TPV). Also, we conducted experiments in order to know the influence of filling balance for runner core pin (RC pin).

• Journal of the Korea Society of Computer and Information
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• v.25 no.2
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• pp.105-111
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• 2020

In this paper, we propose a scheme that minimizes the energy imbalance problem of solar-powered wireless sensor network (SP-WSN) using both a mobile sink capable of wireless power transfer and an efficient clustering scheme (including cluster head election). The proposed scheme charges the cluster head using wireless power transfer from a mobile sink and mitigates the energy hotspot of the nodes nearby the head. SP-WSNs can continuously harvest energy, alleviating the energy constraints of battery-based WSN. However, if a fixed sink is used, the energy imbalance problem, which is energy consumption rate of nodes located near the sink is relatively increased, cannot be solved. Thus, recent research approaches the energy imbalance problem by using a mobile sink in SP-WSN. Meanwhile, with the development of wireless power transmission technology, a mobile sink may play a role of energy charging through wireless power transmission as well as data gathering in a WSN. Simulation results demonstrate that increase the amount of collected data by the sink using the proposed scheme.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.954-955
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• 2015

본 논문에서는 기존 직렬결합 커패시터 입력단을 갖는 7-레벨 인버터에 커패시터 전압균형 제어법을 적용하여 출력 전압의 중간레벨 구간이 제대로 형성되지 않는 문제점을 해결하고자 한다. 기존에 제시된 직렬결합 커패시터 입력단 구성을 갖는 7-레벨 인버터는 2개의 양방향 스위치모듈과 3개의 직렬 연결된 커패시터를 이용한 변형된 Cascaded H-bridge 인버터이다. 기존 논문에서는 입력 전압원으로부터 3개의 직렬 연결된 커패시터의 충전을 통해 레벨을 형성하는 과정에서 커패시터 전압불균형 문제를 해결하지 못하여 결국 출력전압레벨이 7-레벨에서 5-레벨로 감소하는 것을 볼 수 있다. 본 논문에서는 세 개의 직렬결합된 커패시터중 중앙에 위치한 커패시터의 충 방전량을 조절하여 커패시터 전압불균형 문제를 해결한다. 제어법의 타당성은 PSIM 기반의 컴퓨터 시뮬레이션을 통하여 기존 스위칭 제어법과 비교하여 검증한다.

• Transactions of Materials Processing
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• v.13 no.7
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• pp.580-585
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• 2004

Almost all injection molds have multi-cavity runner system fur productivity and are designed with geometrically balanced runner system in order to minimize filling imbalance between cavity to cavity during processing. However, filling imbalances have been observed though geometrically balanced runner lay-out. Generally, these filling imbalances are due to thermal unbalance, viscosity, characteristic of polymers and so on. These kinds of filling imbalances have already been reported by Beaumont since 1997, but his research has mainly focused on filling imbalance at binary runner. In this study, we conducted an experimental study about the filling imbalances in unary branch runner as well as binary branch runner and inquired into the causes of filling imbalances. The results could be summarized as fellowing: Filling imbalances existed in multi-cavity mold with unary branch runner, it could be decreased by optimizing processing condition such as increasing injection rate, and it is almost proportion to each polymer's temperature sensibility.

• Polymer(Korea)
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• v.33 no.6
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• pp.561-568
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• 2009

Small injection molded articles are generally molded by multi-cavity injection molding. The most important thing in multi-cavity molding is flow imbalance among the cavities because it affects the physical property and the quality of products. The cavity filling balance can be achieved by flow balance in the runner through the thermal balance. In this study, novel screw type runner or helical type runner has been developed for the flow balance in the runner and performed experiment and computer simulation. Flow balance has been observed using various screw type runners for several resins such as amorphous and crystalline polymers including low and high viscosities grades. Flow balance experiments have been performed for various injection speeds since the flow balance can be affected by injection speed among the injection conditions. Experimental results have been compared with computational results and they showed good agreement. The cavity filling balance can be achieved by the screw runner where the temperature distribution is uniform through the circulation flow along the screw channel in the screw runner. It has been verified that the novel screw runner is very effective device in flow balance in the multi-cavity injection molding. cavity filling imbalance, multi-cavity injection molding, runner design, screw runner, thermal balance.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.3
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• pp.98-102
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• 2009

Almost all injection molds have multi-cavity runner system for mass production, which are designed with geometrically balanced runner system in order to accomplish filling balance between cavity to cavity during processing. However, even though geometrically balanced runner is used, filling imbalance has been observed. Filling imbalance could be decreased by modifying processing conditions such as injections rate, mold temperature, injection pressure, melt temperature that are related to shear, viscosity. In this study, a series of experiment was conducted to investigate filling imbalance variation when modifying runner layout and polymer and to determine which processing condition influences as the primary cause of filling imbalance in geometrically balanced runner system. The filling imbalance was decreased up to result range of $3{\leq}DFI{\leq}8(%)$ by using a new runner system for balanced filling.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.10
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• pp.144-149
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• 2008

Configuration of filling imbalance which is originated from imbalanced share rate of melt on runner is changed by runner layout, runner shape, material property, injection pressure, injection speed, melt temperature and mold temperature. In this paper, we conducted a study of runner layout and shape that are main factors of filling imbalance. Other factors such as the sharp corner effect and the groove corner effect are recently released were also considered. The results of study are showed that filling rate of between inside and outside cavity was influenced on shape of runner. Especially, this study suggests a new runner system for filling balance by adapting the two effects of unary branch type runner at multi cavity mold and theoretical investigated flow in the sharp corner type runner.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.415-416
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• 2014

FCEV(Fuel Cell Electric Vehicle)는 연료전지를 사용하여 차량 구동용 전동기에 필요한 에너지를 공급한다. 연료전지는 부하에 급격한 변화가 발생하였을 시에 과도특성이 나타나고 자동차에 에너지를 공급하는 속도에 영향을 준다. 그러므로 연료전지의 특성상 FCEV에서 배터리는 연료전지와 함께 사용된다. FCEV 및 전기자동차는 배터리의 대용량화를 위해 일반적으로 배터리 셀을 직/병렬로 모듈화하여 사용하는데, 이때 배터리 모듈의 충전 및 방전이 반복될 경우, 각 배터리 잔존용량의 불균형이 나타난다. 본 논문은 연료전지 전기자동차용 전력변환 장치를 이용하여 배터리 셀을 모듈화하여 모듈 별 밸런싱을 수행하는 시스템의 설계와 제어기법을 제안한다. 각각의 배터리 모듈과 연료전지를 연결하는 컨버터 모듈은 독립적으로 제어되어 배터리를 모듈 단위로 균등화시킨다. 이때 연료전지를 입력으로 절연형 컨버터를 병렬로 사용하며, 각각의 배터리 모듈을 균일하게 충전한다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.451-452
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• 2019

본 논문은 과충전 및 과방전의 원인이 되는 배터리팩 내부 셀의 불균형으로 인한 셀 간 전압 편차를 분석하기 위해 24s 1p로 구성된 배터리 팩을 사용하여 전기적 열화 실험을 진행하였다. 만충 만방 실험 결과에서 SOC 구간에 따른 셀 간 전압 편차를 분석하였으며, 사이클 증가로 인한 열화와 상관관계가 높은 구간을 분석하여 열화 판단의 파라미터로 제안한다.

• Polymer(Korea)
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• v.38 no.2
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• pp.144-149
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• 2014

Large residual stresses are remained in the conventional injection molded products because of the high cavity pressure in packing phase during injection molding process. Conventional injection molding (CIM) invokes distribution of cavity pressure and it has a limitation to obtain product with uniform physical property. Multi-cavity conventional injection molding contains quality deviation among the cavities since flow imbalance occurs during filling phase. Injection compression molding (ICM) is adopted to overcome these limitations of CIM. In this study, molding characteristics of CIM and ICM have been investigated using multi-cavity injection mold. Researches were performed by both experiment and computer simulation through observations of birefringence for transparent resins, polycarbonate and polystyrene in CIM and ICM. As a result, low and uniform birefringence and mold shrinkage were showed in the specimens by ICM that could give a uniform cavity pressure. Deviation of physical property among the specimens in multi-cavity mold shown in CIM was significantly reduced in the specimens by ICM. Through this study it was concluded that the ICM in multi-cavity molding was valid for molding products with uniform property in an individual cavity and also reduced property deviation among the cavities.