• Journal of Computing Science and Engineering
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• 제4권2호
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• pp.128-152
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• 2010

With the advance of computer and communication technologies, wireless sensor networks (WSNs) are increasingly used in many aspects of our daily life. However, since the battery lifetime of WSN nodes is restricted, the WSN lifetime is also limited. Therefore, it is crucial to determine this limited lifetime in advance for preventing service interruptions in critical applications. This paper proposes a feasible static analysis approach to estimating the worstcase lifetime of a WSN. Assuming known routes with a given sensor network topology and SMAC as the underlying MAC protocol, we statically estimate the lifetime of each sensor node with a fixed initial energy budget. These estimations are then compared with the results obtained through simulation which run with the same energy budget on each node. Experimental results of our research on TinyOS applications indicate that our approach can safely and accurately estimate worst-case lifetime of the WSN. To the best of our knowledge, our work is the first one to estimate the worst-case lifetime of WSNs through a static analysis method.

• 소성∙가공
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• 제29권5호
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• pp.272-281
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• 2020

As the thickness of mobile communication devices is getting thinner, the size of the internal parts is also getting smaller. Among them, the battery case requires a high-level deep drawing technique because it has a rectangular shape with a large aspect ratio. In this study, the initial blank shape was optimized to minimize earing in a multi-stage deep drawing process using an artificial neural network(ANN). There has been no reported case of applying artificial neural network technology to the initial blank optimal design for a square case with large aspect ratio. The training data for ANN were obtained though simulation, and the model reliability was verified by performing comparative study with regression model using random sample test and goodness-of-fit test. Finally, the optimal design of the initial blank shape was performed through the verified ANN model.

• 대한한방내과학회지
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• 제40권5호
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• pp.832-840
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• 2019

Objective: The aim of this case report was to present the effects of traditional Korean medicine on a patient with Broca's aphasia associated with cerebral hemorrhage after middle cerebral artery infarction. Methods: The Korean version of the Western Aphasia Battery (K-WAB) and the Evaluation of Articulator Performance were used to evaluate the language functions of the patient. Herbal medication and acupuncture were administered to improve the patient's symptoms. Results: The inpatient and outpatient treatments improved the patient's symptoms. The aphasia quotient (AQ) score of the K-WAB test before treatment was 6.4, but it increased to 21.4 after treatment. The Evaluation of Articulator Performance score improved by 0.0 points before treatment, by 1.0 points after 9 days of treatment, and by 1.5 points after 42 days of treatment. Conclusions: This case report suggest that Korean medical therapy can be effective in improving the language functions of patients with Broca's aphasia.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.318-321
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• 2003

In case, sensor system performs where it is difficult to access physically and it is in the poor environment, it is limited to communicate by using wire and installing power module in sensor system. In this paper, it suggests how information is obtained from telemetry sensor by means of inductive coupling without battery. Comparing with the telemetry sensor system of inductive coupling by the power supply, this system estimates the capacitance of sensor with high precision in using RLSE, not the process of modulation and demodulation. In order to activate this system, inductive model is used and in case of time variant parameter, telemetry sensor system which has got high rate in accuracy is implemented by using the forgetting factor.

• 전기학회논문지
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• 제66권10호
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• pp.1460-1465
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• 2017

Outage areas can be transferred to adjacent feeders to restore power supply in case of the fault on the distribution system. Feeders in the small island or mountain area may not have backup feeders due to the low density of load. In this weakly meshed open loop system, BESS can be used as a backup feeder to improve reliability of power supply. This paper proposes a new network reconfiguration method for BESS based service restoration. Fuzzy decision making technique is adopted to deal with fuzziness of service restoration planning rules. Case studies using KEPCO real distribution system have been performed to verify feasibility of the proposed method.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2007년도 학술대회
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• pp.394-400
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• 2007

This thesis aims the development of power supply for the BTS of Mobile Telecommunication system. Specially, it receives AC power and it can be possible both supply the uninterrupted and stabile DC Power to BTS and simultaneously maintain full charging the back-up battery that is used in case failing AC power supply. In addition, easy maintenance is also the main purpose of it regardless of front and left side except rear side. In these days, it needs more small size power supply system in order to comply with the user needs regarding more easy maintenance and more less space as become smaller main telecommunication systems. This system can be installed close to wall and support more easy maintenance and it was considered easy expansion in case when it needs.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.959-965
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• 2009

To meet the demand increasing passengers in railway vehicles, railway transportation service companies are increasing the numbers of cars per train-set. Two solutions, Variable train-set formations and Multiple train-set operation, are common way to increase the transportation capability. These kind of long distance train-set can effect train-set command and control system, and sometimes the digital signals using train line from master cabin can not reach to the systems located the other extremity slave car. This is so called Voltage Drop. This phenomenon is originated from the electrical power consumption and electrical cable resistance, and cause to the equipments or cars located end of the electrical cable way, malfunction or abnormal operations. This voltage drop happens not only in train lines but also Battery Power Lines. The purpose of this investigation is to design high reliability railway vehicles by clarifying the possibility of happening these events case by case, by analyzing the reasons, and finally by finding the best solutions.

• 한국화재소방학회논문지
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• 제33권4호
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• pp.59-69
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• 2019

본 논문은 ESS 리튬배터리의 과충전 및 외부수열에 따른 화재위험성에 관한 실험적 연구이다. 과충전 실험결과 벤트 발생 후 가연성 가스 및 연기가 서서히 증가되다 착화가 발생했고, 충전된 에너지가 한순간에 급격히 방출되면서 화염분출 및 불티를 동반한 폭발적인 연소형태가 나타났다. 반면, 외부수열 실험결과 벤트 발생 후 엄청난 양의 가연성 가스 및 연기가 다량 배출되다 착화되어, 방출된 에너지로 인해 충전된 에너지양 자체가 급격히 감소되어 화염발생 후 과충전과 비교했을 때 소극적인 연소형태가 나타났다. 소손특성 분석결과 육안 및 X-ray 검사를 통해 과충전과 외부수열(외부화염)의 차이점을 찾을 수 있었다. 즉, 과충전의 경우 내부 극판이 완전히 파괴되어 부서지고, 극판에서 천공이 관찰되었으나, 외부수열의 경우 내부 전극판의 소손정도가 심하지 않고 형태를 유지하고 있었다.

• Korean Chemical Engineering Research
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• 제60권4호
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• pp.473-477
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• 2022

본 연구에서는 폐배터리 재활용 공정에서 발생하는 공정폐액 중 리튬 회수를 위한 후보 기술들을 검토하고 상용화 관점에서 해당 공정에 적용 가능한 기술들을 정성적 측면에서 검토하였다. 현재 기술 수준에서 상용화 규모로 적용 가능한 증발법, 침전 및 용매추출 기술이 있다. 증발법의 경우 대규모의 땅을 필요로 하고 농축과정에서의 Li 손실로 낮은 회수율 보여 적용하기 어렵다. 침전의 경우, 상용화되어 있는 기술로 인산의 높은 Li/Na 선택도로 높은 회수율을 보이지만 비싼 인산 사용으로 회수 단계 필요로 공정이 복잡하고 Li 농축과정에서 고체를 다루고 있어 연속운전이 불가능하다는 단점이 있다. 용매추출의 경우, Li/Na 선택도가 높은 저렴한 추출제를 찾는다면 전 단계의 다른 금속 추출 시 사용되고 있는 방법으로 연속운전이 가능하고 Li 농축 시 액체 상태이기 때문에 연속운전이 가능하다는 장점이 있다. 침전기술과 비교하여 유사한 회수율을 보인다면 상용화가 가능성이 가장 높을 것이다.

• 한국산학기술학회논문지
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• 제19권10호
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• pp.590-597
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• 2018

최근 전 세계적으로 에너지 고갈과 기후변화 문제로 인하여, 재생 가능하고 친환경적인 태양광전원에 대한 관심이 증가되고 있다. 그러나, 이러한 태양광전원은 주변 환경에 따라 출력이 크게 변동되는데, 일부 모듈에만 음영이 발생하여도 태양광전원의 전체적인 운용 효율이 상당히 저하되는 문제점을 가지고 있다. 즉, 기존의 제어방식에서는 모듈을 직렬로 연결된 스트링들이 인버터에 연계되어 있으므로, 일부 모듈에 부분 음영이 발생하면 해당 스트링의 전압이 인버터의 동작전압범위를 벗어나게 되어, 해당 스트링이 인버터에서 탈락되는 문제점이 발생할 수 있다. 따라서, 본 논문에서는 음영에 의하여 태양광 스트링이 인버터에서 탈락되는 것을 방지하기 위하여, 태양광스트링에 리튬이온전지를 연결한 태양광전원 운용효율 향상장치의 제어알고리즘을 제안한다. 또한, 전력전자 회로해석 상용 프로그램인 PSIM S/W를 이용하여 태양광스트링, 리튬이온전지, 계통연계형 인버터로 구성된 태양광전원의 운용효율향상장치의 모델링을 수행하여 운용 특성을 분석한 결과, 직렬로 연결된 리튬이온전지가 부분 음영에 의하여 전압 저하를 발생한 해당 스트링의 전압을 보상함으로서, 해당 스트링이 인버터에서 탈락되는 현상을 개선하여 태양광전원의 운용효율을 향상시킬 수 있음을 알 수 있었다.