• The Journal of the Korea institute of electronic communication sciences
• /
• v.13 no.1
• /
• pp.153-162
• /
• 2018

The importance of energy harvesting technique is increasing due to the elevated level of demand for sustainable power sources for wearable device applications. In this study, we developed an Energy Harvesting wearable Platform(EH-P) architecture which is used in the design of a multi-energy source based on TENG. The proposed switching circuit produces power with higher current at lower voltage from energy harvesting sources with lower current at higher voltage. This can powers microcontrollers for a short period of time by using PV and TENG complementarily placed under hard conditions for the sources such as indoors. As a result, the whole interface circuit is completely self-powered with this makes it possible to run of sensing on a Wearable device platform. It was possible to increase the wearable device life time by supplying more than 29% of the power consumption to wearable devices. The results presented in this paper show the potential of multi-energy harvesting platform for use in wearable harvesting applications, provide a means of choosing the energy harvesting source.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.02a
• /
• pp.97-97
• /
• 2010

We demonstrate the hybrid polymer-quantum dot based multi-functional device (Organic bistable devices, Light-emitting diode, and Photovoltaic cell) with a single active-layer structure consisting of CdSe/ZnS semiconductor quantum-dots (QDs) dispersed in a poly N-vinylcarbazole (PVK) and 1,3,5-tirs- (N-phenylbenzimidazol-2-yl) benzene (TPBi) fabricated on indium-tin-oxide (ITO)/glass substrate by using a simple spin coating technique. The multi-functionality of the device as Organic bistable device (OBD), Light Emitting Diode (LED), and Photovoltaic cell can be successfully achieved by adding an electron transport layer (ETL) TPBi to OBD for attaining the functions of LED and Photovoltaic cell in which the lowest unoccupied molecular orbital (LUMO) level of TPBi is positioned at the energy level between the conduction band of CdSe/ZnS and LiF/Al electrode (band-gap engineering). Through transmission electron microscopy (TEM) study, the active layer of the device has a p-i-n structure of a consolidated core-shell structure in which semiconductor QDs are uniformly and isotropically adsorbed on the surface of a p-type polymer core and the n-type small molecular organic materials surround the semiconductor QDs.

• KIPE Magazine
• /
• v.6 no.6
• /
• pp.56-58
• /
• 2001

오늘날 PC성능의 향상으로 인하여, PC용 EDA제품들이 봇물처럼 쏟아져 나오고 있다. 이중에서 현재 20,000이상의 구매 사이트를 가지고 있는 Electronics Workbench사의 MultiSIM 2001을 소개하고자 한다. 현재의 PC용 EDA제품들의 초점은 저렴한 가격,편한 사용환경과 다양한 기능, 그리고 얼마나 다양한 device모델을 지원하는가를 초점으로 경쟁하고 있다. 이러한 관점에서 MultiSIM 2001을 분석하였다.

• Journal of the Korean Society of Radiology
• /
• v.13 no.4
• /
• pp.605-611
• /
• 2019

The purpose of this study is to manufacture a multi-function device (MFD) which can be applied to various types of weight-bearing view of the lower leg, and to compare the results with the images from the existing weight-bearing platforms (WBPs), thereby suggesting a clinical utilization. The MFD was manufactured, by considering the minimum adjustable heights of the platform for weight-bearing foot/ankle, platform for hindfoot alignment view, and X-ray tube of the X-ray device. A foot/ankle phantom was used to take the images of weight-bearing lateral foot in MFD and WBPs to compare the resolutions of the X-ray images using a quick modulation transfer function (MTF) program. Between both the images taken from the MFD and WBPs, there was no statistically significant difference found in the mean cycles per pixel (C/P) and the lines per image height (LPH) of the 50%-Contrast Spatial Frequency (MTF50), and 10-90% of Maximum Energy Rise Distance (10-90%), where p>0.05. The MFD is suggested for its clinical trial as a useful positioning device that can secure the patient's safety and manifoldly perform various inspections. Also, the recommendation of the positioning device as a policy can activate dedicated manufacturers, while also improving the quality of medical services.

• Journal of IKEEE
• /
• v.20 no.1
• /
• pp.94-102
• /
• 2016

This paper proposes a new prediction method to reduce times and labor of repetitive multi-physics simulation. To achieve exact results from the whole simulation processes, complex modeling and huge amounts of time are required. Current multi-physics analysis focuses on the simulation method itself and the simulation environment to reduce times and labor. However this paper proposes an alternative way to reduce simulation times and labor by exploiting machine learning algorithm trained with data set from simulation results. Through comparing each machine learning algorithm, Gaussian Process Regression showed the best performance with under 100 training data and how similar results can be achieved through machine-learning without a complex simulation process. Given trained machine learning algorithm, it's possible to predict the result after changing some features of the simulation model just in a few second. This new method will be helpful to effectively reduce simulation times and labor because it can predict the results before more simulation.

• Journal of Soil and Groundwater Environment
• /
• v.25 no.4
• /
• pp.58-66
• /
• 2020

Since the typical horn-type ultrasonic equipment induces a reaction at the probe tip, the sonochemical reaction has a limitation that it occurs only in a specific area. As one of the ways to overcome this limitation, an ultrasonic device with multi-stepped horn equipped with several oscillators has been developed. The objective of this study was to investigate the sonochemical effects induced by acoustic cavitation system in 20 kHz multi-stepped ultrasonic horn using calorimetry, KI dosimetry and the luminol test. The sonochemical effects of multi-stepped ultrasonic horn were compared with that of the typical horn-type 20 kHz ultrasonic device. The effect of immersion depth and power on the sonochemical reaction was investigated in the ultrasonic system with multi-stepped ultrasonic horn. Higher calorimetric energy was obtained at higher immersion depth and power conditions. Sonochemical effects increased significantly when using the high immersion depth and input power. However, as the input power increased, the cavitation reaction zone concentrated around the ultrasonic horn. Additionally, the experiments to examine the effect of liquid temperature was conducted. The smaller sonochemical reaction was obtained for the higher liquid temperature. The effect on temperature seems to be closely related to liquid conditions such as viscosity and vapor pressure of water.

• Journal of Sensor Science and Technology
• /
• v.23 no.5
• /
• pp.342-348
• /
• 2014

This paper introduced a novel multi-gas sensor detector with simple signal processing algorithm. This device was evaluated by investigating the characteristics of combustible materials using fire-generated smell and smoke. Plural sensors including TGS821, TGS2442, and TGS260X were equipped to detect carbon monoxide, hydrogen gas, and gaseous air contaminants which exist in cigarette smoke, respectively. Signal processing algorithm based on the difference of response times in fire-generated gases was implemented with early and accurately fire detection from multiple gas sensing signals. All fire experiments were performed in a virtual fire chamber. The cigarette, cotton fiber, hair, polyester fiber, nylon fiber, paper, and bread were used as a combustible material. This analyzing software and sensor controlling algorithm were embedded into 8-bit micro-controller. Also the detected multiple gas sensor signals were simultaneously transferred to the personnel computer. The results showed that the air pollution detecting sensor could be used as an efficient sensor for a fire detector which showed high sensitivity in volatile organic compounds. The proposed detecting algorithm may give more information to us compared to the conventional method for determining a threshold value. A fire detecting device with a multi-sensor is likely to be a practical and commercial technology, which can be used for domestic and office environment as well as has a comparatively low cost and high efficiency compared to the conventional device.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.7
• /
• pp.2972-2991
• /
• 2016

WLAN is the best choice in the place where complex network is hard to set up. Intelligent terminals are more and more assembled in some areas now. However, according to IEEE 802.11n/802.11ac, the access-point (AP) can only serve one user at a single frequency channel. The spectrum efficiency urgently needs to be improved. In theory, AP with multi-antenna can serve multiple users if these users do not interfere with each other. In this paper, we propose a user clustering scheme that could achieve multi-user selection through the mutual cooperation among users. We focus on two points, one is to achieve multi-user communication with multiple antennas technique at a single frequency channel, and the other one is to use a way of distributed users' collaboration to determine the multi-user selection for user clustering. Firstly, we use the CSMA/CA protocol to select the first user, and then we set this user as a source node using users' cooperation to search other proper users. With the help of the users' broadcast cooperation, we can search and select other appropriate user (while the number of access users is limited by the number of antennas in AP) to access AP with the first user simultaneously. In the network node searching, we propose a maximum degree energy routing searching algorithm, which uses the shortest time and traverses as many users as possible. We carried out the necessary analysis and simulation to prove the feasibility of the scheme. We hope this work may provide a new idea for the solution of the multiple access problem.

• Journal of Electrical Engineering and information Science
• /
• v.1 no.2
• /
• pp.109-118
• /
• 1996

This paper deals with a new multi-level high voltage source inverter with GTO Thyristors. Recently, a multi-level approach seems to be the best suited for implementing high voltage conversion systems because it leads to harmonic reduction and deals with safe high power conversion systems independent of the dynamic switching characteristics of each power semiconductor device. A conventional multi-level inverter has some problems; voltage unbalance between DC-link capacitors and larger blocking voltage across the inner switching devices. To solve these problems, the novel multi-level inverter structure is proposed.

• Convergence Security Journal
• /
• v.14 no.2
• /
• pp.11-16
• /
• 2014

Recently, request of IPTV was increase. It is a multi-screen service by used TV, PC, and smart-phones. Especially, IPTV and smart-phone linked multi-screen service are very growth by user's recommends. Now, IPTV have a security service partial and multi-screen service. But smart-phone and multi-screen service don't have security service. And authentication service for smart-phone and IPTV linked multi-screen service is don't.. Therefore, We propose that user authentication system for multi-screen service with IPTV and multi-device linked authentcation services. Our proposed system base on Kerberos, so proposal is easy and fast about user authentication. This have simple procedures and more secure services against of PKI. So, our system can support secure multi-screen services against various security threats in multi-screen environments.