• Journal of IKEEE
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• v.21 no.4
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• pp.368-374
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• 2017

In this Paper, we developed a low power type LED security light using LED lighting that substitutes a 220[V] commercial power source for a solar cell module instead of a halogen or a sodium lamp. in addition, a PWM type drive control circuit is designed to minimize the heat generation problem and the drive current of the LED drive controller. in developed system, The light efficiency measurement value is 93.6[lm/W], and a high precision temperature sensor is used inside the controller to control the heat generation of the LED lamp. In order to eliminate the high heat generated from the LED lamp, it is designed to disperse quickly into the atmosphere through the metal insertion type heat sink. The heat control range of LED lighting was $50-55[^{\circ}C]$. The luminous flux and the lighting speed of the LED security lamp were 0.5[s], and the beam diffusion angle of the LED lamp was about $110[^{\circ}C]$ by the light distribution curve based on the height of 6[m].

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.2
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• pp.97-104
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• 2017

In this paper, we designed and fabricated the multi band Transceiver Assembly(TCA) for the Multi Channel Synthetic Aperture Radar(MCSAR) containing C-band, X-band, Ku-band and we researched to verify electrical performance of TCA. The transceiver consists of transmitters, receivers, signal selection modules for each band, and stability oscillator, frequency synthesizer, controller, power distributor. The transceiver has a receive path selection and bandwidth selection functions in accordance with the operating mode. And the transceiver can transmit and receive all three bands simultaneously, each band has a bandwidth of up to 300 MHz. Final transmission output of transceiver for each band is over 20 dBm to be suitable for driving the T/R module. Receiver bandwidth is selected according to the required function and receiver gain has approximately C-band 52 dB, X-band 50 dB, Ku-band 60 dB, the maximum noise figure of Ku-band V polarization is 4.28 dB in the whole band H, V polarization. As a result of the electrical performance test, a multi-band TCA is satisfied the property requirements of the MCSAR.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.3
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• pp.517-526
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• 2008

A one-chip DC-DC converter circuit for OLED(Organic Light-Emitting Diode) display module of automotive clusters is newly proposed. OLED panel driving voltage circuit, which is a charge-pump type, has improved characteristics in miniaturization, low cost and EMI(Electro-Magnetic Interference) compared with DC-DC converter of PWM(Pulse Width Modulator) type. By using bulk-potential biasing circuit, charge loss due to parasitic PNP BJT formed in charge pumping, is prevented. In addition, the current dissipation in start-up circuit of band-gap reference voltage generator is reduced by 42% and the layout area of ring oscillator is reduced by using a logic voltage VLP in ring oscillator circuit using VDD supply voltage. The driving current of VDD, OLED driving voltage, is over 40mA, which is required in OLED panels. The test chip is being manufactured using $0.25{\mu}m$ high-voltage process and the layout area is $477{\mu}m{\times}653{\mu}m$.

• Journal of the Korea Convergence Society
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• v.12 no.1
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• pp.243-250
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• 2021

In the medical field, applications of plasma are applied sterilize instruments mainly but with the advent of bio-plasma technology, the scope of application is expanding. Recently, In addition, high-density miniaturization with handheld is required for sophisticated procedures when irradiated directly or treated with non-standard conditions. Rosen-type PZT is a device with a structure that generates high voltage plasma by achieving voltage transformation through electro-mechanical coupling using piezoelectric effect.and is used in portable plasma generating devices as an advantage to increase energy density relatively. In this paper, Rosen-type PZT was modeled using equivalent circuits and was carried out and a plasma generating device for medical application was designed and prototype tested. Prototype plasma generating device generates an output voltage of 5.8 kV with 12V input power and is designed to operate at high voltage by applying the half-bridge topology power converter. The results of the study confirmed the availability of various medical devices, such as plasma jets or direct exposure equipment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.26 no.2
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• pp.91-111
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• 2024

Most of utility cable tunnels are constructed utilizing shield TBM as part of the underground transmission line project. The TBM chamber is the only space inside the tunnel that encounters rock and soil, and is the place with the highest frequency of accident exposure, such as collapse and collision accidents. Since there is currently no way to measure the disc cutter wear from outside the chamber, frequent inspection by workers is essential. Accordingly, in this study, in order to prevent safety accidents inside the TBM chamber and expect the effect of shortening the construction period by reducing the number of chamber openings, the concept of disk cutter wear measurement technology was established and a prototype was produced. By considering prior technology and determining that magnetic sensors are most suitable for the excavation environment, wear measurement sensor package were developed integrating magnetic sensors, wireless communication modules, power supply, external casing, and monitoring systems. To verify the performance of the prototype in an actual excavation environment, a full-scale tunnelling test was performed using a 3.6 m EPB shield TBM. Based on the full-scale tests, five prototypes were operated normally among eight prototypes. It was analyzed that sensor measurement, wireless communication, and durability performance were secured within a maximum thrust of 3,000 kN and a rotation speed of 1.5 RPM.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.3
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• pp.153-163
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• 2017

The objective of this study is to enhance the model's speed of estimating weather variables (e.g., minimum/maximum temperature, sunshine hour, PRISM (Parameter-elevation Regression on Independent Slopes Model) based precipitation), which are applied to the Agrometeorological Early Warning System (http://www.agmet.kr). The current process of weather estimation is operated on high-performance multi-core CPUs that have 8 physical cores and 16 logical threads. Nonetheless, the server is not even dedicated to the handling of a single county, indicating that very high overhead is involved in calculating the 10 counties of the Seomjin River Basin. In order to reduce such overhead, several cache and parallelization techniques were used to measure the performance and to check the applicability. Results are as follows: (1) for simple calculations such as Growing Degree Days accumulation, the time required for Input and Output (I/O) is significantly greater than that for calculation, suggesting the need of a technique which reduces disk I/O bottlenecks; (2) when there are many I/O, it is advantageous to distribute them on several servers. However, each server must have a cache for input data so that it does not compete for the same resource; and (3) GPU-based parallel processing method is most suitable for models such as PRISM with large computation loads.

• Korean Chemical Engineering Research
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• v.60 no.1
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• pp.86-92
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• 2022

Recently, the bio-healthcare market is enlarging worldwide due to various reasons such as the COVID-19 pandemic. Among them, biometric measurement and analysis technology are expected to bring about future technological innovation and socio-economic ripple effect. Existing systems require a large-capacity battery to drive signal processing, wireless transmission part, and an operating system in the process. However, due to the limitation of the battery capacity, it causes a spatio-temporal limitation on the use of the device. This limitation can act as a cause for the disconnection of data required for the user's health care monitoring, so it is one of the major obstacles of the health care device. In this study, we report the concept of a standalone healthcare monitoring module, which is based on both triboelectric effects and electromagnetic effects, by converting biomechanical energy into suitable electric energy. The proposed system can be operated independently without an external power source. In particular, the wireless foot pressure measurement monitoring system, which is rationally designed triboelectric sensor (TES), can recognize the user's walking habits through foot pressure measurement. By applying the triboelectric effects to the contact-separation behavior that occurs during walking, an effective foot pressure sensor was made, the performance of the sensor was verified through an electrical output signal according to the pressure, and its dynamic behavior is measured through a signal processing circuit using a capacitor. In addition, the biomechanical energy dissipated during walking is harvested as electrical energy by using the electromagnetic induction effect to be used as a power source for wireless transmission and signal processing. Therefore, the proposed system has a great potential to reduce the inconvenience of charging caused by limited battery capacity and to overcome the problem of data disconnection.