• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.2
• /
• pp.395-400
• /
• 2017

The paper discussed the air-to-fuel ratio control of automotive fuel-injection systems using the cerebellar model articulation controller(CMAC) neural network. Because of the internal combustion engines and fuel-injection's dynamics is extremely nonlinear, it leads to the discontinuous of the fuel-injection and the traditional method of control based on table look up has the question of control accuracy low. The advantages about CMAC neural network are distributed storage information, parallel processing information, self-organizing and self-educated function. The unique structure of CMAC neural network and the processing method lets it have extensive application. In addition, by analyzing the output characteristics of oxygen sensor, calculating the rate of fuel-injection to maintain the air-to-fuel ratio. The CMAC may easily compensate for time delay. Experimental results proved that the way is more good than traditional for petrol control and the CMAC fuel-injection controller can keep ideal mixing ratio (A/F) for engine at any working conditions. The performance of power and economy is evidently improved.

• Journal of Korean Society on Water Environment
• /
• v.23 no.2
• /
• pp.236-243
• /
• 2007

Fluorescence measurements of dissolved organic matter (DOM) have the superior advantages over other analysis tools for the applications to water quality management due to their rapid analysis. It is known that protein-like fluorescence characteristics are well corelated with microbial activities and biodegradable organic matter. In this study, potential biochemical oxygen demand (BOD) predictor were explored using the fluorescence peak intensities and/or the integrated fluorescence intensities derived from synchronous fluorescence spectra and the first derivative spectra of river samples. A preliminary study was conducted using a mixture of a river and a treated sewage to test the feasibility of the approach. It was demonstrated that the better BOD predictor can be derived from synchronous fluorescence spectra and the derivatives when the difference between the emission and the excitation wavelengths (${\Delta}{\gamma}$) was large. The efficacy of several selected fluorescence parameters was rivers in Seoul. The fluorescence parameters exhibited relatively good correlation coefficients with the BOD values, ranging from 0.59 to 0.90. Two parameters were suggested to be the optimum BOD predictors, which were a fluorescence peak at a wavelength of 283 nm from the synchronous spectrum at the ${\Delta}{\gamma}$ value of 75 nm, and the integrated fluorescence intensity of the first derivatives of the spectra at the wavelength range between 245 nm and 280 nm. Each BOD predictor showed the correlation coefficients of 0.89 and 0.90, respectively. It is expected that the results of this study will provide important information to develop a real-time efficient sensor for river BOD in the future.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.15 no.5
• /
• pp.2953-2961
• /
• 2014

Dementia once occurred is known to be mostly irreversible but can be treated only if it is detected early; especially vascular Dementia. Thus, in this paper we have developed Dementia diagnosis and care application through inter-working between biometric sensors and smart phone. With developing serious game for the demented elderly, we proposed ons-stop solution for Dementia; smart-phone application with diagnosis, prevention and mitigation of Dementia. Since the proposed game for mitigating Dementia requires sense of space and balance using both arms instead of operating simple arrow button, a treatment effect for Dementia will be doubled. If we tried to forestall, ease and cure Dementia with the proposed application. the social losses from Dementia would be minimized as a result.

• Journal of Sensor Science and Technology
• /
• v.30 no.5
• /
• pp.309-313
• /
• 2021

Organic semiconductors have received tremendous attention for their research because of their tunable electrical and optical properties that can be achieved by changing their molecular structure. However, organic materials are inherently unstable in the presence of oxygen and moisture. Therefore, it is necessary to develop moisture and air stable semiconducting materials that can replace conventional organic semiconductors. In this study, we developed a NiO_x thin film through a solution process. The electrical characteristics of the NiO_x thin film, depending on the thermal annealing temperature and UV-ozone treatment, were determined by applying them to the hole injection layer of an organic light-emitting diode. A high annealing temperature of 500 ℃ and UV-ozone treatment enhanced the conductivity of the NiO_x thin films. The optimized NiO_x exhibited beneficial hole injection properties comparable those of 1,4,5,8,9,11-hexaazatriphenylene hexacarbonitrile (HAT-CN), a conventional organic hole injection layer. As a result, both devices exhibited similar power efficiencies and the comparable electroluminescent spectra. We believe that NiO_x could be a potential solution which can provide robustness to conventional organic semiconductors.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.25 no.1
• /
• pp.19-28
• /
• 2021

In rotating detonation engine(RDE), only the detonation wave is moving around the outer wall of the combustor. Neither a mechanical part nor flow is rotating in RDE. Thus, the RDE cross section is not necessary to be circular, but arbitrary closed section is possible. A RDE of tri-arc cross section is designed and As an example of an arbitrary cross sectioned RDE, a RDE of tri-arc cross section is designed in this study, and operational and performance characteristics were examined experimentally. The rotation of the detonation wave is confirmed by dynamic pressure sensor and high-speed camera, while the characteristics of the detonation wave were investigated at the concave and convex surfaces. In the present study, the thrust level of 17.0 N to 96.0 N was obtained depending on the mass flow rate.

• Journal of Internet of Things and Convergence
• /
• v.9 no.1
• /
• pp.41-47
• /
• 2023

Today, due to the increase in global population growth, the international community is discussing solving the food problem. The aquaculture industry is emerging as an alternative to solving the food problem. For the innovative growth of the aquaculture industry, smart fish farms that combine the fourth industrial technology are recently being distributed, and full-cycle digitalization is being promoted. Water quality sensors, which are important in the aquaculture industry, are electrochemical portable sensors that check water quality individually and intermittently, making it impossible to analyze and manage water quality in real time. Recently, optically-based monitoring sensors have been developed and applied, but the reliability of monitoring data cannot be guaranteed because the state information of the water quality sensor is unknown. Therefore, this paper proposes an algorithm representing self-diagnosis status such as Failure, Out of Specification, Maintenance Required, and Check Function based on monitoring data collected by water quality sensors to ensure data reliability.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2022.10a
• /
• pp.28-30
• /
• 2022

Recently, the number of confirmed cases has increased again with the new variant of COVID-19. Quarantine is recommended, especially to prevent the rapidly increasing spread, as environmental controls, such as minimizing contact with others, can increase safety. In addition, there are often cases in which the patient's condition cannot be confirmed from the standpoint of a guardian, such as visitation being prohibited under certain conditions. At this time, the sensor data values of oxygen, carbon dioxide concentrations, temperature and humidity, and alcohol, which are medical gases used in hospitals, are collected remotely using ZigBee wireless communication technology. Design a system that can be stored and monitored in a database. We propose an environmental monitoring system, which is a visualization system designed to allow hospitals to check and feedback data on the managed environment, and to give reliability to parents.

• Composites Research
• /
• v.36 no.5
• /
• pp.342-348
• /
• 2023

There has been increasing demand for real-time monitoring of body and ambient temperatures using wearable devices. Graphene-based thermistors have been developed for high-performance flexible temperature sensors. In this study, the temperature coefficient of resistance (TCR) of monolayer graphene was controlled by coating polyethylenimine (PEI) on graphene surfaces to enhance its temperature-sensing performances. Monolayer graphene grown by chemical vapor deposition (CVD) was wet-transferred onto a target substrate. To facilitate the interfacial doping by PEI, the hydrophobic graphene surface was altered to be hydrophilic by oxygen plasma treatments while minimizing defect generation. The effect of PEI doping on graphene was confirmed using a back-gated field-effect transistor (FET). The CVD-grown monolayer graphene coated with PEI exhibited an improved TCR of -0.49(±0.03) %/K in a temperature range of 30~50℃.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.19 no.3
• /
• pp.119-123
• /
• 2013

Simplified control logic was devised to fabricate and operate the modified atmosphere (MA) container of fresh produce equipped with gas-diffusion tube whose opening/closing was controlled in response to real time $O_2$ concentration. This is a simplified ramification of the previously developed control logic using both $O_2$ and $CO_2$ concentrations ([$O_2$] & [$CO_2$]). The developed logic was applied to and tested by a container system filled with spinach at $10^{\circ}C$ having optimum MA window of [$O_2$] of 7~10% and [$CO_2$] of 5~10%. It was shown that setting the proper on-off limit (11%) for $O_2$ control based on the assumed relationship $[O_2]+[CO_2]$=21% could attain the desired $CO_2$ concentration just below the upper tolerance limit ($[CO_2]_H$, 10%). The $O_2$ control point can be the lower tolerance limit or adjusted one (21-$[CO_2]_H$) depending on the commodity's MA requirement. The developed logic using single $O_2$ sensor could attain the equilibrated [$O_2$] of 11% with [$CO_2$] of 8~9% which was desired and similar to that of its predecessor ([$O_2$] of 9~10% with [$CO_2$] of 10%) using both $O_2$ and $CO_2$ sensors. Both MA containers (one only with single $O_2$ sensor control and one with $O_2$ and $CO_2$ sensors) could also keep the spinach quality without significant difference between them, but significantly better than perforated control package of air.

• Journal of Sensor Science and Technology
• /
• v.2 no.1
• /
• pp.101-108
• /
• 1993

$TiO_{2}$/Se : Te heterojunction for color sensor has been fabricated by RF reactive sputtering and thermal evaporation methods onto glass substrate. The optimum deposition condition of $TiO_{2}$ films was such that RF power was 120 W, substrate temperature was $100^{\circ}C$, oxygen concentration was 50%, working pressure was 50 mTorr for the $TiO_{2}$ film thickness of $1000{\AA}$. In this case, the optical transmittance of $TiO_{2}$ film at 550 nm-wavelength was 85%, resistivity was $2{\times}10^9{\Omega}{\cdot}cm$, refractive index was 2.3, and optical bandgap was 3.58 eV. The composition ratio of 0 to Ti by AES analysis was 1.7. When $TiO_{2}$ films were annealed at $400^{\circ}C$ for 30 min. in $O_{2}$ ambient, the optical transmittance of $TiO_{2}$ films at the wavelength range of $300{\sim}580$ nm was improved from 0 to 25%. When Se : Te films were annealed at $190^{\circ}C$ for 1 min., photosensitivity under illumination of 1000 lux was 0.75. The optical bandgap of Se : Te films was 1.7 eV. The structures of Se : Te films were the hexagonal with (100) and (110) orientation. The spectral response of a-Se was improved by the addition of Te, especially in the long wavelength region. The $TiO_{2}$/Se : Te heterojunction showed wide spectral response, and more improved one than that of a-Si film in the blue light region.