• 전력전자학회논문지
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• 제17권2호
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• pp.114-120
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• 2012

Recently, integrated electric propulsion system has been vigorously adopted into naval vessels. To enhance effectiveness and efficiency of power management in these propulsion systems, this paper investigates necessity of energy storage devices and their operation strategies. By introducing the energy storage devices, engine can operate at higher efficiency point and accordingly costs for fuel and maintenance are significantly reduced. In addition, transient performance can also be improved with support of the devices and it leads to stable operation of shipboard power bus. To validate the proposal of this paper, computer simulation has been conducted with real load data of existing electric propulsion system.

• Advances in nano research
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• 제14권6호
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• pp.527-539
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• 2023

Measuring energy burn during intensive combat sport has been a challenging concerns for a long time. In the present article, the energy consumption during combat sports is measured by use of wearable GoBe2 equipped with nanotechnology measuring devices. In this regard, 12 professional combat athletes were asked to wear GoBe2 devices during different sessions of intensive combat exercises. The curves provided by GoBe2 nano-sensor devices are further collected and analyzed for different combat durations. On the other hand, energy consumption in these athlete is calculated using other validated methods to evaluate reliability of GoBe2 wearable devices. Based on the results obtained from these experiments a multi-parameter mathematical model is presented for estimation of combat calorie consumptions. The results show that nanotechnology in these type of sensors could help in estimation of calorie consumption during combat. Moreover, the reliability of using wearable GoBe2 sensors are satisfactory except for some specific conditions. The mathematical model provides a satisfactory results based on athlete physical condition and also duration of the combat with about 8% error margin in the results.

• Medical Lasers
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• 제9권1호
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• pp.34-38
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• 2020

Recently, various lasers and energy-based devices (EBDs) have been widely used in aesthetic procedures. Although using lasers and energy-based aesthetic procedures presents a potential risk to doctors, nurses, and patients, aesthetic procedures tend to be performed without the necessary precautions. For injury prevention, it is essential to follow safety rules and be aware of potential accidents. Furthermore, it is important to understand the basic principles of the devices, including the different optical and electrical properties. Acquiring the exact knowledge to control a device is important for two reasons; to maintain a safer operating environment and prolong the lifespan of expensive devices. This review briefly summarizes the knowledge needed for better and safer aesthetic procedures and the proper control of aesthetic devices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.12-12
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• 2011

Interfacing functional materials with electrical or biological systems is of prime importance in terms of expanding applicative fields and obtaining high performances of devices. Herein, I report the functionalization of graphenes through supramolecular assembly and their electrochemical applications into fuel cells, supercapacitors, and biosensor devices. The solution processable nanohybridization of graphenes by functional materials such as ionic liquids, polyelectrolytes, block copolymers, and biomaterials, described herein would pave the way to obtain high performances of flexible energy and biosensor devices as well as to overcome the existing technology barriers.

• 센서학회지
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• 제31권5호
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• pp.293-300
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• 2022

Flexible, wearable, and implantable electronic sensors have started to gain popularity in improving the quality of life of sick and healthy people, shifting the future paradigm with high sensitivity. However, conventional technologies with a limited lifespan occasionally limit their continued usage, resulting in a high cost. In addition, traditional battery technologies with a short lifespan frequently limit operation, resulting in a substantial challenge to their growth. Subsequently, utilizing human biomechanical energy is extensively preferred motion for biologically integrated, self-powered, functioning devices. Ideally suited for this purpose are piezoelectric energy harvesters. To convert mechanical energy into electrical energy, devices must be mechanically flexible and stretchable to implant or attach to the highly deformable tissues of the body. A systematic analysis of piezoelectric nanogenerators (PENGs) for personalized healthcare is provided in this article. This article briefly overviews PENGs as self-powered sensor devices for energy harvesting, sensing, physiological motion, and healthcare.

• Journal of Power Electronics
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• 제19권4호
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• pp.1054-1067
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• 2019

This paper systematically investigates the influence of device parameters spread on the current distribution of paralleled silicon carbide (SiC) MOSFETs. First, a variation coefficient is introduced and used as the evaluating norm for the parameters spread. Then a sample of 30 SiC MOSFET devices from the same batch of a well-known company is selected and tested under the same conditions as those on datasheet. It is found that there is big difference among parameters spread. Furthermore, comprehensive theoretical and simulation analyses are carried out to study the sensitivity of the current imbalance to variations of the device parameters. Based on the concept of the control variable method, the influence of each device parameter on the steady-state and transient current distributions of paralleled SiC MOSFETs are verified separately by experiments. Finally, some screening suggestions of devices or chips before parallel-connection are provided in terms of different applications and different driver configurations.

• 정보처리학회논문지:소프트웨어 및 데이터공학
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• 제5권5호
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• pp.209-220
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• 2016

최근 스마트폰, 태블릿과 같은 기기의 사용량이 증가하면서, 이에 탑재되는 소프트웨어는 더욱 복잡해지고 규모가 커지고 있다. 배터리의 전력으로 구동되는 모바일 기기들은 전력 공급의 한계로 인해 운용시간을 증가시키는 것이 중요한 이슈이다. 최근에는 소프트웨어 동작이 하드웨어 구동을 통해 전력 소모를 일으킨다는 점에서, 효율적인 동작 패턴을 갖는 소프트웨어 개발에 대한 연구들이 진행되고 있다. 그러나 모바일 기기에 탑재되는 소프트웨어는 그 개발 주기가 짧은 경우가 많아 최적화와 전력 소모량을 반영하기 어려운 경우가 많다. 따라서 본 연구에서는 소모전력 절감을 위한 코드 리팩토링 기법을 제안하여, 소프트웨어 개발 및 유지보수에서 보다 용이하게 저전력 요구사항을 충족시키고자 한다. 이를 위해 전력 소모량을 감소시킬 수 있는 코드 패턴에 대하여 Energy Bad Smell을 식별하고, 이를 제거하기 위한 새로운 코드 리팩토링 기법을 제안하며, 실험을 통해 그 효용성을 검증하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 영호남학술대회 논문집
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• pp.331-334
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• 2000

The organic electroluminescent(EL) device has gathered much interest because of its large potential in materials and simple device fabrication. We fabricated EL devices which have a blended single emitting layer containg poly(Nvinylcarbazole)[PVK] and poly(3-dodecylthiophene)[P3DoDT]. The molar ratio between P3DoDT and PVK changed with 1:0, 2:1 and 1:1. To improve the external quantum efficiency of EL devices, we applied insulating layer, LiF layer between polymer emitting layer and AI electrode. All of the devices emit orange-red light and it's can be explained that the energy transfer occurs from PVK to P3DoDT. Within the molar ratio 1:0, 2:1 and 1:1, the energy transfer was not saturated, which results in the not appearance of PVK emission in the blue region. In the voltage-current and voltage-light power characteristics of devices applied LiF layer, current and light power drastically increased with increasing with applied voltage. In the consequence of the result, the light power of the device have a molar ratio 1:1 with LiF layer was about 10 times larger than that of the device without PVK at 6V.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.593-603
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• 2019

In wearable healthcare systems, sensor devices can be deployed in places around the human body such as the stomach, back, arms, and legs. The sensors use tiny batteries, which have limited resources, and old sensor batteries must be replaced with new batteries. It is difficult to deploy sensor devices directly into the human body. Therefore, instead of replacing sensor batteries, increasing the lifetime of sensor devices is more efficient. A transmission power control (TPC) algorithm is a representative technique to increase the lifetime of sensor devices. Sensor devices using a TPC algorithm control their transmission power level (TPL) to reduce battery energy consumption. The TPC algorithm operates on a closed-loop mechanism that consists of two parts, such as sensor and sink devices. Most previous research considered only the sink part of devices in the closed-loop. If we consider both the sensor and sink parts of a closed-loop mechanism, sensor devices reduce energy consumption more than previous systems that only consider the sensor part. In this paper, we propose a new approach to consider both the sensor and sink as part of a closed-loop mechanism for efficient energy management of sensor devices. Our proposed approach judges the current channel condition based on the values of various body sensors. If the current channel is not optimal, sensor devices maintain their current TPL without communication to save the sensor's batteries. Otherwise, they find an optimal TPL. To compare performance with other TPC algorithms, we implemented a TPC algorithm and embedded it into sensor devices. Our experimental results show that our new algorithm is better than other TPC algorithms, such as linear, binary, hybrid, and ATPC.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권6호
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• pp.668-676
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• 2017

A two-dimensional numerical investigation is performed to study the influence of slot width of multi-stage stationary floating overtopping wave energy devices on overtopping flow rate and performance. The hydraulic efficiency based on captured crest energy of different device layouts is compared with that of single-stage device to determine the effect of the geometrical design. The results show optimal trends giving a huge increase in overtopping energy. Plots of efficiency versus the relative slot width show that, for multi-stage devices, the greatest hydraulic efficiency is achieved at an intermediate value of the variable within the parametric range considered, relative slot width of 0.15 and 0.2 depending on design layouts. Moreover, an application of adaptive slot width of multi-stage device is investigated. The numerical results show that the overall hydraulic efficiency of non-adaptive and adaptive slot devices are approximately on par. The effect of adaptive slot width on performance can be negligible.