• 태양에너지
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• 제19권4호
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• pp.33-43
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• 1999

The study on ice thermal storage system is to improve total system performance and increase the economical efficiency in actual all-conditioning facilities. To obtain the high charging and discharging efficiencies in ice thermal storage system, the improvement of thermal stratification is essential, therefore the process flow must be piston flow in the cylindrical type. With the relation of the aspect ratio(H/D) in the storage tank, the stratification is formed better as inlet flow rate is smaller. If the inlet and the outlet port are settled at the upside and downside of the storage tank, higher storage rate could be obtainable. In case that the flow directions inside the thermal storage tank are the upward flow in charging and the downward in discharging, thermal stratification is improved because the thermocline thickness is maitained thin and the degree of stratification increases respectively. In the charging process, in case of inlet flow rate the thermal stratification has a tendency to be improved with the lower flow rate and smaller temperature gradient in case of inlet temperature, the large temperature difference between inflowing water and storage water are influenced from the thermal conduction. The effect of the reference temperature difference is seen differently in comparison with the former study for chilled and hot water. In the discharging process, the thermal stratification is improved by the effect of the thermal stratification of the charging process.

• 한국정밀공학회지
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• 제33권12호
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• pp.965-970
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• 2016

Fuel used in the steel metallurgy industry is stored in huge stage systems called SILO. Fuel is released by RDM (Rotary Discharge Machine), at the place of utilization. RDM is located in the Silo, and is constituted of a main frame, driving part, discharging part and control part. RDM is combined to a direct motion on the rail in tunnel, having a rotary motion enabled by a motor. In this paper, we calculate the theoretical discharging capacity of RDM to confirm the correlation between design element and discharging capacity of RDM. Also, through structure analysis, we confirm the vulnerable point of RDM when it discharges the storage materials. We hope to apply these results to design a more efficient RDM.

• Korean Chemical Engineering Research
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• 제55권4호
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• pp.483-489
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• 2017

The loss of the sulfur cathode material through dissolution of the polysulfide into electrolyte causes a significant capacity reduction of the lithium-sulfur cell during the charge-discharge reaction, thereby debilitating the electrochemical performance of the cell. We addressed this problem by using a chemical and physical approach called reduction of polysulfide dissolution through direct coating functional inorganic (graphene oxide) or organic layer (polyethylene oxide) on electrode, since the deposition of external functional layer can chemically interact with polysulfide and physically prevent the leakage of lithium polysulfide out of the electrode. Through this approach, we obtained a composite electrode for a lithium-sulfur battery (sulfur: 60%) coated with uniform and thin external functional layers where the thin external layer was coated on the electrode by solution coating and drying by a subsequent heat treatment at low temperature (${\sim}80^{\circ}C$). The external functional layer, such as inorganic or organic layer, not only alleviates the dissolution of the polysulfide electrolyte during the charging/discharging through physical layer formation, but also makes a chemical interaction between the polysulfide and the functional layer. As-formed lithium-sulfur battery exhibits stable cycling electrochemical performance during charging and discharging at a reversible capacity of 700~1187 mAh/g at 0.1 C (1 C = 1675 mA/g) for 30 cycles or more.

• 한국화재소방학회논문지
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• 제24권6호
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• pp.54-60
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• 2010

본 연구는 할론 계열의 소화약제를 대체할 수 있는 청정소화약제인 질소가스를 생산하는 산업용 질소발생기를 사용하여 임의 방호구역에 대한 질소발생기의 방사압력에 따른 방사량을 결정할 수 있는 상관관계식을 실험적으로 결정하였다. 질소발생기의 방사량을 결정할 수 있는 상관관계식을 결정하기 위하여 간단한 방호구역을 제작하여 소형 질소발생기에서 발생하는 질소가스의 방사압과 방사량을 변화시키며 방호구역 내의 산소농도 변화를 실험적으로 파악하였다. 실험결과를 가지고 무유출인 경우 임의 방호구역에 대한 소화약제 방사량과 산소농도와의 관계를 정의한 이론식에 대하여 실험한 산소농도와의 차이를 분석하여 실험결과에 가장 근접하는 상관관계식을 결정하였다. 결정한 상관관계식은 임의 방호구역, 방사압력 및 방사량에 대하여 실험하여 검증한 결과 비교적 잘 일치하였다. 따라서 본 연구를 통하여 결정된 상관관계식을 이용하여 임의 방호구역에 대한 질소발생기의 방사량을 결정할 수 있는 방사량 결정 선도를 완성하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.275-275
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• 2007

Two sorts of electrode composed of Sulpur/CNT/PVDF and Silver/CNT/PVDF were prepared by in situ chemical method and their electrochemical performance were evaluated by using cyclic voltammetry, impedance measurement and constant-current charge/discharge cycling technique. Also, composite electrodes were characterized by FE-SEM and BET. Raw materials such as CNT/Silver and CNT/Sulfur were mixed in ethanol, dried. These mixed materials were heated at 900 and $320^{\circ}C$ for 2hr, respectively in order to enhance contact among CNT electrodes. Electric double layer capacitor cells were fabricated using these mixed powder with polymer of PVDF. For the charging and discharging characteristics measured at scan rate of 1 mA/s, Supercapacitor of Sulphur-CNT-PVDF electrode showed a better performance than that of Ag-CNT-PVDF, which seems to be related with lower contact resistance of Sulphur-CNT-PVDF electrode.

• 한국인터넷방송통신학회논문지
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• 제23권4호
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• pp.171-176
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• 2023

21세기 현대사회에 있어서 이차전지 배터리(Battery)를 이용한 휴대용 전자제품은 계속해서 경량, 소형화되어가는 추세 속에서 있다. 그리고 이러한 추세와 더불어 우리는 몸에 착용할 수 있는 전자 장비를 이용하여 하루 일상생활에서 정보를 수집, 공유하는 4차 산업혁명 시대에 활동하고 있다. 따라서 소형 가전제품 및 디지털 기기를 사용하면서 재충전할 수 있는 이차전지 배터리의 역할은 점점 더 중요하게 증가하고 있다. 이러한 증가와 더불어 이차전지 배터리 성능시험은 특성, 수명, 고장진단, 재활용 등의 다양한 시험방법을 요구하고 있으며 있다. 또한 배터리의 안전과 적절한 기능을 보장하기 위한 배터리 테스트 시스템 구축과 이에 따른 지침 및 올바른 기본지식이 고려되고 있다. 따라서 본 논문에서는 배터리의 성능과 직접으로 연결된 시나리오별 충방전에 따른 이차전지 리튬이온(Li-ion) 배터리의 특성에 대해 살펴보고자 한다.

• 한국인터넷방송통신학회논문지
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• 제24권2호
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• pp.133-138
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• 2024

리튬이온 배터리는 높은 에너지 밀도 빠른 충전조건 긴 사이클수명의 특성으로 여러 분야에서 사용되고 있다. 하지만 리튬이온 배터리는 과충전, 과방전, 물리적손상, 고온에서의 사용은 배터리 수명 감소와 보호회로 손상에 의한 화재 및 폭발에 의한 인명피해를 입힐 수 있다. 이러한 배터리의 위험성을 낮추며 배터리 성능을 향상시키기 위해서는 충전 및 방전 과정에서의 특성들을 분석하고 이해하여야 한다. 따라서 본 논문에서는 배터리 충방전기와 시뮬레이터를 활용하여 리튬이온 배터리의 충전 및 방전 특성을 분석하여 과충전 과방전에 따른 배터리 수명 감소와 보호회로 손상에 의한 화재 및 폭발에 의한 인명피해를 줄이고자 한다.

• Journal of Power Electronics
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• 제15권6호
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• pp.1438-1445
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• 2015

A new DC-DC power converter is researched for renewable energy and battery hybrid power supplies systems in this paper. At the charging mode, a renewable energy source provides energy to charge a battery via the proposed converter. The operating principle of the proposed converter is the same as the conventional DC-DC buck converter. At the discharging mode, the battery releases its energy to the DC bus via the proposed converter. The proposed converter is a non-isolated high step-up DC-DC converter. The coupled-inductor technique is used to achieve a high step-up voltage gain by adjusting the turns ratio. Moreover, the leakage-inductor energies of the primary and secondary windings can be recycled. Thus, the conversion efficiency can be improved. Therefore, only one power converter is utilized at the charging or discharging modes. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(2)
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• pp.85-88
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• 2001

This paper suggests an improved switch architecture for the rechargeable battery protection IC. In the existing protection IC, charging and discharging switches composed of the CMOS transistor and the diode are external components. It is difficult to integrate the switches in a CMOS process due to the large chip-size overhead and inevitable parasitic effects. In this paper, we propose a new switch architecture of the MOSFET's 'diode connection' method. The performance and chip-size overhead are proved to be adequate for the fully integrated protection IC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1531-1533
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• 1997

We prepared polyimide film by electrophoretic deposition onto glass film as a sensing materials of humidity, and treated with plasma discharging as a function of discharging power to improve performance of the sensor. Then evaluated the characteristics of polyimide on humidity.