• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.6
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• pp.732-741
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• 2018

In order to maximize the usable capacity of a BMS (battery management system) that uses several battery cells connected in series, a cell balancing technique that equips each cell with the same voltage is needed. In the active cell balancing circuit using a multi-winding transformer, a balancing circuit that transfers energy directly to the cell (cell-to-cell) is composed of a PMOS switch and a gate driving chip for driving the NMOS switch. The TLP2748 photocoupler and the TLP2745 photocoupler are required, resulting in increased cost and reduced integration. In this paper, instead of driving PMOS and NMOS switching devices by using photocoupler, we proposed 70V BCD process based PMOS gate driving circuit, NMOS gate driving circuit, PMOS gate driving circuit and NMOS gate driving circuit with improved switching time. ${\Delta}t$ of the PMOS gate drive switch with improved switching time was 8.9 ns and ${\Delta}t$ of the NMOS gate drive switch was 9.9 ns.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.6
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• pp.897-906
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• 2022

In this paper, we propose a novel MAC protocol based on the harmonic transmission of ACK, called HAT-LoRa, for improving the reliability and the utilization in multiple gateway LoRa Networks. LoRa is basically vulnerable to collision due to the primitive pure ALOHA-like MAC. Whereas data frame delivery can be guaranteed by the transparent bridge of multiple receiving gateways, ACK is still transmitted by a single gateway in LoRa Network. HAT-LoRa provides the augmented reception opportunity of ACK via the simultaneous transmissions of identical ACK in multiple spreading factors. The proposed method reduces the expected transmission times of ACK double gateway environment as well as single gateway environment, by 55 and 60% in maximum, by 35% and 40% in average, in a single- and double-gateway environment, respectively. Especially, it outperforms under the environment where the distance between end device and gateways are similar to each other.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.615-617
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• 2005

오늘날 공장 자동화에 이용되는 필드버스 네트워크는 여러 가지가 있으며 이들은 각각의 미디어 접근 방식과 프로토콜을 사용하고 있다. 이러한 필드버스 네트워크는 완전히 분리되어 있기 때문에 네트워크 관리자는 이를 관리하는데 많은 어려움을 겪고 있다. 본 논문에서는 이기종의 필드버스 네트워크를 통합할 수 있는 필드버스 프로토콜 변환 게이트웨이를 설계하였다. 필드버스 프로토콜 변환 게이트웨이는 프로토콜 변환을 하여 다른 종류의 네트워크로 데이터를 전달할 수 있고 분리된 네트워크를 통합하고 통합된 환경으로 제어 및 모니터링을 가능하게 한다.

• Journal of IKEEE
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• v.16 no.2
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• pp.116-120
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• 2012

We reported on a high performance InGaAs/InAlAs metamorphic HEMT with 50 nm gate length on a GaAs substrate. The fabricated $50nm{\times}60{\mu}m$ MHEMT showed good DC and RF characteristics. Typical drain current density of 740 mA/mm and extrinsic transconductance(gm) of 1.02 S/mm were obtained with our devices. The current gain cut-off frequency(fT) and maximum oscillation frequency(fmax) obtained for the fabricated MHEMT device were 430 GHz and 406 GHz, respectively.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.543-544
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• 2014

In this paper, we present the design of a compound sensing platform to share environment information with other smart devices such as a gateway, a phone, a pad, etc. The proposed compound sensing platform is designed as a single-board hardware to support air temperature and humidity, soil temperature and humidity, solar visible radiation, etc. It sends the measured information to a smart gateway which shares the information with smart phones and pads by Twitter.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.6
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• pp.1-6
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• 2010

We present simulation results on DC characteristics of AlGaN/GaN HEMT having stair-type gate electrodes, in comparison with those of the conventional single gate AlGaN/GaN HEMTs and field-plate enhanced AlGaN/GaN HEMTs. In order to reduce the internal electric field near the gate electrode of conventional HEMT and thereby to increase their DC characteristics, we applied three-layered stacking electrode schemes to the standard AlGaN/GaN HEMT structure. As a result, we found that the internal electric field was decreased by 70% at the same drain bias condition and the transconductance (gm) was improved by 11.4% for the proposed stair-type gate AlGaN/GaN HEMT, compared with those of the conventional single gate and field-plate enhanced AlGaN/GaN HEMTs.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1959-1968
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• 2016

The recent automobiles, a number of ECU inside the vehicle has been used. Also, each ECU is connected to different types of networks in accordance with the characteristics. Therefore, efficient data exchange between discrete network has emerged as a very important element. The gateway is responsible for the ability to exchange data between discrete network. In this study, we propose the new gateway algorithm to provide the structure of the mapping table to improve the efficiency of data exchange between discrete network. Also it provides a structure of a new gateway algorithm with a function of adjusting the priority of the data to be transmitted to another network arbitrarily. Moreover, the proposed gateway structure may simultaneously convert the transmission data input from a particular network to multiple networks. Another advantage is easy to change the entire data structure only if we change the table structure in the gateway.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.637-641
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• 2006

We present the DC and RF characteristics of 100 nm gate length InGaAs/InAlAs/GaAs metamorphic high electron mobility transistors (MHEMTs). We fabricated the T-gate with 100 nm foot print by using a positive resist ZEP520/P (MMA-MAA)/PMMA trilayer by double exposure method. The fabricated 100 nm MHEMT with a $70\;{\mu}m$ unit gate width and two fingers were characterized through do and rf measurements. The maximum drain current density of 465 mA/mm and extrinsic transconductance $(g_m)$ of 844 mS/mm were obtained with our devices. From rf measurements, we obtained the current gain cut-off frequency $(f_T)$ of 192 GHz, and maximum oscillation frequency $(f_{max})$ 310 GHz.

• The Journal of the Korea Contents Association
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• v.4 no.4
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• pp.123-131
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• 2004

Internet is absolutely contributed to information technology revolution nowadays. Internet services such as voice and data, etc. are provided home or small office via home gateway. The development of communication equipment via home gateway is implemented rapidly, and its product various. This paper presents the design and implementation of the VoIP equipment including the telephone function based on the embedded environment and being connected to the home gateway and the PC because of taking 2-ethernet LAN ports. As developing environment, the STLC1502 developed at ST Microelectronics as single chip solution, VxWorks as RTOS, and C language as coding mechanism are used. The verification of the developed systems for the voice test is carried out for the gatekeeper via Internet. The performance parameter is considered as the call processing capacity measuring the time of the call setup and clearing, and the data processing capacity for the file transfer. As a call setup and clearing is about 95ms, the call processing capacity is about 10 calls per second. The data processing capacity is 5.7Mbps in case of file transfer of server and client environment. Therefore the performance result is satisfied in the aspect of the call processing time and the data transfer time in Internet.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.947-949
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• 2013

개인 휴대단말기로부터 측정된 생체정보 데이터가 PHR에 데이터베이스화되기 위해서는 응용 계층 표준 프로토콜인 HL7 CDA 표준에 따라야 한다. 하지만 국제 표준 HL7 CDA는 병원 시스템 간 의료정보 전달을 위한 프로토콜이기 때문에 개인 건강 기기로부터 측정된 생체 정보가 IEEE 11073 PHD 표준에 준하여 전달하더라도 HL7 CDA 프로토콜과 연동될 수 없다. 즉, 모바일 단말기 기반의 u-헬스케어 모니터링 서비스를 위해서는 IEEE 11073 PHD와 HL7 CDA 간 메시지 변환 게이트웨이가 필요하다. 이에 본 논문에서는 개인 휴대단말기를 통해 원격지에 있는 의료진이 사용자의 생체데이터를 실시간 관리하기 위해 ISO/IEEE 11073과 HL7 CDA 간 메시지 변환 게이트웨이 및 HL7 기반 진단지원시스템을 설계하였다.