• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.959-964
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• 2001

An experimental investigation on the near-field electromagnetic loss of thin copper layers has been presented using microfabricated microwave transceivers for applications to multi-chip microsystems. Copper layers in the thickness range of 0.2$\mu$m∼200$\mu$m have been electroplated on the Pyrex glass substrates. Microwave transceivers have been fabricated using the 3.5mm$\times$3.5mm nickel microloop antennas, electroformed on the silicon substrates. Electromagnetic radiation loss of the copper layers placed between the microloop transceivers has been measured as 10dB∼40dB for the wave frequency range of 100MHz∼1GHz. The 0.2$\mu$m-thick copper layer provides a shield loss of 20dB at the frequencies higher than 300MHz, whereas showing a predominant decreases of shield loss to 10dB at lower frequencies. No substantial increase of the shield effectiveness has been found for the copper shield layers thicker that 2 $\mu$m.

• Journal of Korea Multimedia Society
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• v.16 no.1
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• pp.75-86
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• 2013

This paper presents a technique to implement embedded systems using interrupts of the one-chip microcontroller with many peripherals based on a multiple finite state machines model. The multiple finite state machine model utilizes the structure of FSMD used for hardware design and the features of flow control by interrupts. The main finite state machine corresponds to the main program and the sub-state machines corresponds to the interrupt subroutines. Therefore, interrupts from the peripherals can be processed immediately in the sub-state machines. The request and reply variables are used to interface between the finite state machines. Additional operating system is not necessary for the context switching between the main state machine and the sub-state machine, because the flow-control caused by interrupt can be replaced with the switching. An embedded system modeled on multiple finite state machine with ASM charts can be easily implemented by the conversion of ASM charts into C-language programs. This implementation technique can be easily adopted to the hardware oriented embedded systems because of the detail description of the model and the fast response to the interrupt events in the sub-state machine.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1264-1271
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• 2009

In this paper, the chip slot antenna which is used for mobile devices and designed for multi-band is proposed. The proposed antenna is comprised of a chip antenna(10 mm$\times$20 mm$\times$1.27 mm) and a system circuit board(30 mm$\times$60 mm$\times$0.8 mm). The chip slot antenna is mounted on the system circuit board and the end of F-type strip line which is patterned on the chip antenna is connected by a via with a ground plane of the system circuit board. So, a chip antenna radiates effectively the energy by transition between a microstrip line of the system circuit board and a open slot structure of the chip antenna. In the results of proposed antenna, impedance bandwidth of 3:1 VSWR(-6 dB return loss) is 1.98 GHz(1.61~3.59 GHz) and 0.8 GHz(5.2~6 GHz). So, it can cover multi-band of DCS, PCS, UMTS, WLAN. The proposed antenna can be applied to mobile devices.

• Korean Chemical Engineering Research
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• v.50 no.4
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• pp.733-737
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• 2012

This study reports the microfluidic preparation of monodisperse multiple emulsions using hydrodynamic control. To generate multiple emulsions, we fabricate a microfluidic capillary device based on co-flowing stream without any surface modification of microchannels. Based on the system, we can successfully generate multiple emulsions (W/O/W) using water containing 0.5 wt% Tween 20, n-hexadecane with 5 wt% Span 80, and 10 wt% poly (vinyl alcohol) (PVA) aqueous solution, respectively. Furthermore, we control the number of inner droplets by modulation of flow rate of inner fluid at fixed flow rate of middle and outer fluid. The multiple emulsions having precisely controlled inner droplets' size and number can be applicable for multiple chemical reactions as an isolated microreactor.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.689-690
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• 2011

본 논문에서는 무선 센서네트워크 환경에 적용할 수 있는 불법 침입자를 감지하는 시스템으로 GPS의 위성시간과 단말기 노드 내부의 암호화 동기 시간 설정 알고리즘을 혼합하여 시간 중심의 암호화 인증시스템을 설계하여 불법적인 외부노드의 침입을 탐지하는 방법을 제안하고자 한다. 본 논문에서는 GPS의 시간 정보와 RTC(Real Time Clock) 칩과 동기화 하여 시간 정보를 실내에서도 사용할 수 있으며, 마이크로프로세서 내부 타이머 설정 시간 등을 고려하여 다중화된 시간 정보를 이용하여 보다 높은 수준의 침입 감지 시스템을 개발하여 효율성을 제시하고자 한다.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3142-3144
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• 2000

청각시스템의 저전력 및 가격의 저렴화를 위해 달팽이관의 BM(Basilar Membrain)모델을 아날로그 VLSI 마이크로 파워 공정으로 구현하고 있다. Lyon and Mead는 실리론 공정으로 달팽이관 모델을 효과적으로 구현하였다. 이는 단순 직렬 연결된 구조로 각 채널의 지연시간의 차이로 인해 인식율이 떨어질 수 있다. 본 논문에서는 소리의 주파수 정보 추출기능을 하는 직렬 연결된 트리구조(TSBF:Tree-structured Cascaded Bandpass Filter)의 16채널의 아날로그 중간대역통과 필터회로를 CMOS VLSI 공정을 이용하여 설계하였다. 직렬 연결된 저대역통과필터와 고대역통과필터로 각 채널의 중간대역통과 필터를 구현하였다. 이러한 구조에서는 각 채널의 지연시간이 동일하므로 인식율을 높일 수 있다. 그리고 고대역통과필터를 1-poly 디지털 공정으로 구현 가능하고 기생 캐패시터의 영향을 적게 받는 구조로 설계하였다.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.4
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• pp.149-154
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• 2018

This paper describes the fabrication and heat transfer property of 50 watts rated LED array module where multiple chips are mounted on chip-on-board type ceramic-metal hybrid substrate with high heat dissipation property for high power street and anti-explosive lighting system. The high heat transfer ceramic-metal hybrid substrate was fabricated by conformal coating of thick film glass-ceramic and silver pastes to form insulation and conductor layers, using thick film screen printing method on top of the high thermal conductivity aluminum alloy heat-spreading panel, then co-fired at $515^{\circ}C$. A comparative LED array module with the same configuration using epoxy resin based FR-4 PCB with thermalvia type was also fabricated, then the thermal properties were measured with multichannel temperature sensors and thermal resistance measuring system. As a result, the thermal resistance of the ceramic-metal hybrid substrate in the $4{\times}9$ type LEDs array module exhibited about one third to the value as that of FR-4 substrate, implying that at least triple performance of heat transfer property as that of FR-4 substrate was realized.