• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.1000-1002
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• 2005

In the Bluetooth piconet in which up to 7 slave devices can be connected simultaneously at one network instance, the wireless data expected to be sent over to the RF interface should be sliced by the unit of 1 micrometer, which is a requirement in the specification of the Bluetooth version 1.1. In this contribution, we have designed a digital low-pass filter which is able to slice the unstable analog signal fed from the RF interface to the Baseband, by the uniform unit of 1 micrometer, and is also capable of removing the possible noise which can be caused by the analog circuit system. The low-pass filter operated well in the various modes of the Bluetooth RF embedded Baseband chip such as sleep mode, normal mode, and high-speed mode at 12MHz, 24MHz, and 48MHz respectively.

• Journal of information and communication convergence engineering
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• v.13 no.2
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• pp.139-143
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• 2015

A push-push voltage controlled dielectric resonator oscillator (VCDRO) with a modified frequency tuning structure using broadside couplers is investigated. The push-push VCDRO designed at 16 GHz is manufactured using a low temperature co-fired ceramic (LTCC) technology to reduce the circuit size. The frequency tuning structure using a broadside coupler is embedded in a layer of the A6 substrate by using the LTCC process. Experimental results show that the fundamental and third harmonics are suppressed above 15 dBc and 30 dBc, respectively, and the phase noise of push-push VCDRO is -97.5 dBc/Hz at an offset frequency of 100 kHz from the carrier. The proposed frequency tuning structure has a tuning range of 4.46 MHz over a control voltage of 1-11 V. This push-push VCDRO has a miniature size of 15 mm×15 mm. The proposed design and fabrication techniques for a push-push oscillator seem to be applicable in many space and commercial VCDRO products.

• Journal of the Korean institute of surface engineering
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• v.52 no.5
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• pp.258-264
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• 2019

Assembling heterostructures by combining dissimilar oxide semiconductors is a promising approach to enhance charge separation and transfer in photoelectrochemical (PEC) water splitting. In this work, the CuO nanorods array/$Cu_2O$ thin film bilayered heterostructure was successfully fabricated by a facile method that involved a direct electrodeposition of the $Cu_2O$ thin film onto the vertically oriented CuO nanorods array to serve as the photoelectrode for the PEC water oxidation. The resulting copper-oxide-based heterostructure photoelectrode exhibited an enhanced PEC performance compared to common copper-oxide-based photoelectrodes, indicating good charge separation and transfer efficiency due to the band structure realignment at the interface. The photocurrent density and the optimal photocurrent conversion efficiency obtained on the CuO nanorods/$Cu_2O$ thin film heterostructure were $0.59mA/cm^2$ and 1.10% at 1.06 V vs. RHE, respectively. These results provide a promising route to fabricating earth-abundant copper-oxide-based photoelectrode for visible-light-driven hydrogen generation using a facile, low-cost, and scalable approach of combining electrodeposition and hydrothermal synthesis.

• Journal of Convergence for Information Technology
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• v.9 no.9
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• pp.38-43
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• 2019

In this paper, a method of inputting one analog input and two digital switch inputs by using one analog port of microcontroller embedded in IoT device was proposed. In this method, the upper limit and the lower limit of the input voltage range of the analog input port are determined, and the analog input voltage is input to this interval. The digital switches are configured to exceed the boundaries of the upper and lower limits, respectively. To verify the performance of the proposed method, an experimental circuit was constructed and tested using a microcontroller. As a result, all three inputs can be sensed using a single analog port, thus confirming that the three required input ports are reduced to one input port, ie, 33%.

• Journal of Korea Society of Digital Industry and Information Management
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• v.10 no.4
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• pp.79-87
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• 2014

In this paper, we implemented the HearCAM platform with Raspberry PI B+ model which is an open source platform. Raspberry PI B+ model consists of dual step-down (buck) power supply with polarity protection circuit and hot-swap protection, Broadcom SoC BCM2835 running at 700MHz, 512MB RAM solered on top of the Broadcom chip, and PI camera serial connector. In this paper, we used the Google speech recognition engine for recognizing the voice characteristics, and implemented the pattern matching with OpenCV software, and extended the functionality of speech ability with SVOX TTS(Text-to-speech) as the matching result talking to the microphone of users. And therefore we implemented the functions of the HearCAM for identifying the voice and pattern characteristics of target image scanning with PI camera with gathering the temperature sensor data under IoT environment. we implemented the speech recognition, pattern matching, and temperature sensor data logging with Wi-Fi wireless communication. And then we directly designed and made the shape of HearCAM with 3D printing technology.

• Composites Research
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• v.22 no.3
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• pp.55-59
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• 2009

Microstrip antennas are low profile, are conformable to planar and nonplanar surfaces, are simple and inexpensive to manufacture, mechanically robust when mounted on rigid surfaces and are compatible with MMIC(Monolithic microwave integrated circuit) designs; they have been used in diverse communication systems. The rectangular microstrip patch antenna is designed for a central frequency of 12.5 GHz, and the final product is a $4{\times}1$ array antenna with curvature radius of 200 mm. The microstrip antenna is embedded in a sandwich structure which consists of skin and core material. After impact, the performance of damaged antenna is estimated by measuring the return loss and radiation pattern. The antenna performance was not affected by this impact damage.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.12
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• pp.99-108
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• 2015

The embedded microcontroller which is operated by the logic gates synchronized on the clock pulse, is gradually used as main controller of mission-critical systems. Severe electrical situations such as high voltage/frequency surge may cause malfunctioning of the clock source. The tolerant system operation is required against the various external electric noise and means the robust design technique is becoming more important issue in system clock failure problems. In this paper, we propose on-chip backup clock change architecture for the automatic clock failure detection. For the this, we adopt the edge detector, noise canceller logic and glitch-free clock changer circuit. The implemented edge detector unit detects the abnormal low-frequency of the clock source and the delay chain circuit of the clock pulse by the noise canceller can cancel out the glitch clock. The externally invalid clock source by detecting the emergency status will be switched to back-up clock source by glitch-free clock changer circuit. The proposed circuits are evaluated by Verilog simulation and the fabricated IC is validated by using test equipment electrical field radiation noise

• Korean Journal of Optics and Photonics
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• v.23 no.1
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• pp.12-16
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• 2012

In the paper, we fabricated a Ni master with $45^{\circ}$-mirror structures for flexible waveguide fabrication. The flexible waveguide films with embedded $45^{\circ}$-angled mirrors at the waveguide ends were successfully fabricated using a UV-imprint process. Next, in order to enhance the reflectivity of the mirrors, Ni(3 nm)-Au(200 nm) bilayers were evaporated on the $45^{\circ}$-angled facets through a locally opened thin mask using an electron beam evaporator. We measured propagation loss, bending loss, mirror loss and bending reliability of the fabricated waveguide.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.11-20
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• 1999

The data transfer width between the mocroprocessor and the memory comes to a critical part that limits system performance since the data transfer width has been as it was while the performance of a microprocessor is getting higher due to its continuous development in speed. And it is important that the memory should be in small size for the reduction of embedded microprocessor's price which is integrated on a single chip with the memory and IO circuit. In this paper, a mocroprocessor tentatively named as Extendable Instruction Set Computer(EISC) is proposed as the high code density 32 bit mocroprocessor architecture. The 32 bit EISC has 16 general purpose registers and 16 bit fixed length instruction which has the short length offset and small immediate operand. By using and extend register and extend flag, the offset and immediate operand could be extended. The proposed 32 bit EISC is implemented with an FPGA and all of its functions have been tested and verified at 1.8432MHz. And the cross assembler, the cross C/C++ compiler and the instruction simulator of the 32 bit EISC shows 140-220% and 120-140% higher code density than RISC and CISC respectively, which is much higher than any other traditional architectures. As a consequence, the EISC is suitable for the next generation computer architecture since it requires less data transfer width compared to any other ones. And its lower memory requirement will embedded microprocessor more useful.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.99-107
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• 2006

Magnetic nondestructive testing is very useful far detecting a crack on the surface or near of the surface of the ferromagnetic materials. The distribution of the magnetic flux leakage (DMFL) on a specimen has to be obtained quantitatively to evaluate the crack. The magnetic camera is proposed to obtain the DMFL at the large lift-off. The magnetic camera consists of a magnetic source, magnetic lens, analog to digital converters (ADCs), interface, and computer. The magnetic leakage fields or the distorted magnetic fields from the object, which are concentrated on the magnetic lens, are converted to analog electrical signals tv arrayed small magnetic sensors. These analog signals are converted to digital signals by the ADCs, and are stored, imaged, and processed by the interface and computer. However the magnetic camera has limitations with respect to converting and switching speed, full range and resolution, direct memory access (DMA), temporary storage speed and volume because common ADCs were used. Improved techniques, such as those that introduce the operational amplifier (OP-Amp), amplify the signal, reduce the connection line, and use the low pass filter (LPF) to increase the signal to noise ratio are necessary. This paper proposes the exclusive embedded ADC including OP-Amp, LPF, microprocessor and DMA circuit for the magnetic camera to satisfy the conditions mentioned above.