• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.417-418
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• 2017

납축전지는 충전특성 곡선에 따라 정전류 충전 구간과 정전압 충전 구간으로 나누어 충전 동작을 수행하는 것이 바람직하다. 그러나 플라이백 컨버터를 사용한 저가형 배터리 충전기에서는 컨버터 회로의 1차측과 2차측의 절연을 유지하면서 이러한 2가지의 제어를 수행하는 것이 기술적으로 어려울 뿐만 아니라 회로가 복잡해지므로 현실적으로는 간편하게 정전압 충전만을 사용하는 경우가 대부분이다. 이처럼 정전압 충전만을 사용하게 되면 납축전지에 큰 충전 전류가 흐를 수 있으므로 축전지의 발열이나 수명 단축 등의 문제를 야기할 수 있다. 본 논문에서는 마이크로컨트롤러에 의해 제어되는 디지털 가변저항을 사용하여 실시간으로 전압 피드백을 조절하는 방법으로 정전류 제어가 가능한 새로운 정전류 및 정전압 충전 방식을 제안하였으며, 직접 실험을 통하여 유효성을 확인하였다.

• Kosin Medical Journal
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• v.33 no.3
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• pp.396-401
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• 2018

Extraction of old pacemaker leads remains a complex procedure owing to fibrotic encapsulation and lead adhesions. We report a case of extraction of 15-year-old pacemaker leads by weight and pulley method. A 81-year-old man presented with exposed pacemaker leads out of body with purulent discharge from a pacemaker insertion site. He inserted DDD (dual chamber pacing, dual chamber sensing dual function) pacemaker implantation 15 years ago for SSS. Previously pacemaker battery was removed 3 years ago due to recurrent infection of pacemaker scar site. We extracted the pacemaker leads by weight and pulley method successfully without any complications.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.62-66
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• 2008

The characteristic of the superconducting magnetic energy storage(SMES) system is faster response, longer life time, more economical, and environment friendly than other uninterruptible power supply(UPS) using battery. So, the SMES system can be used to develop methods for improving power quality where a short interruption of power could lead to a long and costly shutdown. Recently, cryogen free SMES has developed using BSCCO(Bismuth Strontium Calcium Copper Oxide) wire. We fabricated and tested the conduction cooling system for the 600 kJ class HTS SMES. The experiment was accomplished for the simulation coils. The simulation coils were made of aluminium, it is equivalent to thermal mass of 600 kJ HTS SMES coil. The coil is cooled with two GM coolers through the copper conduction bar. In this paper, we report that the test results of cool-down and heat loads characteristics of the simulation coils. The developed conduction cooling system adapted to 600 kJ HTS SMES system and cope with the unexpected sudden heat impact, too.

• International journal of advanced smart convergence
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• v.13 no.2
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• pp.25-34
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• 2024

The paper investigates how the semiconductor and electric vehicle industries are addressing safety and security concerns in the era of autonomous driving, emphasizing the prioritization of safety over security for market competitiveness. Collaboration between these sectors is deemed essential for maintaining competitiveness and value. The research suggests solutions such as advanced autonomous driving technologies and enhanced battery safety measures, with the integration of AI chips playing a pivotal role. However, challenges persist, including the limitations of big data and potential errors in semiconductor-related issues. Legacy automotive manufacturers are transitioning towards software-driven cars, leveraging artificial intelligence to mitigate risks associated with safety and security. Conflicting safety expectations and security concerns can lead to accidents, underscoring the continuous need for safety improvements. We analyzed the expansion of electric vehicles as a means to enhance safety within a framework of converging security concerns, with AI chips being instrumental in this process. Ultimately, the paper advocates for informed safety and security decisions to drive technological advancements in electric vehicles, ensuring significant strides in safety innovation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1825-1830
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• 2015

In some cases, despite the pedestrian jaywalking pedestrian traffic lights to red, or even wait for the walk signal to stand down in the driveway. If this is the case may be liable to lead to a traffic accident. Thus, using an infrared sensor wateuna adopted the approach that the warning announcement when a pedestrian enters the driveway, curved pedestrian crossing the intersection in this case, it is difficult to install. In this paper, we propose a Fitness referral system utilizes a built-in sensor of the Android mobile devices. For this purpose, the sensor is a proximity sensor using an acceleration sensor. The proximity sensor has a number of disadvantages compared to the high precision battery power, the acceleration sensor accuracy, fast response time, on the other hand, the disadvantage is the lower. Close to reduce battery consumption of the sensor, BMI of the user sensor control mechanism and increase the accuracy of the acceleration sensor (Body Mass Index) obtained after the index was applied to the recommendation algorithm, which like the movement mechanism.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.37.2-37.2
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• 2010

Recently $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ has been consistently examined and investigated by scientists because of its high lithium storage capacity, which exceeds beyond the conventional theoretical capacity based on conventional chemical concepts. Consequently, $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ is considered as one of the most promising cathode candidates for next generation in Li rechargeable batteries. Yet the mechanism and the origin of the overcapacity have not been clarified. Previously, many authors have demonstrated simultaneous oxygen evolution during the first delithiation. However, it may only explain the high capacity of the first charge process, and not of the subsequent cycles. In this work, we report a clarified interpretation of the structural evolution of $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$, which is the key element in understanding its anomalously high capacity. We identify how the structural evolution of $Li_{1.2}Ni_{0.2}Mn_{0.6}O_2$ occurs upon the electrochemical cycling through careful study of electrochemical profiles, ex-situ X-ray diffraction (XRD), HR-TEM, Raman spectroscopy, and first principles calculation. Moreover, we successfully separated the structural change at subsequent cycles (mainly cation rearrangement) from the first charge process (mainly oxygen evolution with Li extraction) by intentionally synthesizing sample with large particle size. Consequently, the intermediate states of structural evolution could be well resolved. All observations made through various tools lead to the result that spinel-like cation arrangement and lithium environment are created and embedded in layered framework during repeated electrochemical cycling.

• Journal of IKEEE
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• v.21 no.1
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• pp.66-69
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• 2017

In recent year, energy harvesting technologies from the ambient environments such as light, motion, wireless waves, and temperature again a lot of attraction form research community [1-5] due to its efficient solution in order to substitute for conventional power delivery methods, especially in wearable together with on-body applications. The drawbacks of battery-powered characteristic used in commodity applications lead to self-powered, long-lifetime circuit design. Thermoelectric generator, a solid-state sensor, is useful compared to the harvesting devices in order to enable self-sustained low-power applications. TEG based on the Seebeck effect is utilized to transfer thermal energy which is available with a temperature gradient into useful electrical energy. Depending on the temperature difference between two sides, amount of output power will be proportionally delivered. In this work, we illustrated a low-input voltage energy harvesting circuit applied discontinuous conduction mode (DCM) method for getting an adequate amount of energy from thermoelectric generator (TEG) for a specific wearable application. With a small temperature gradient harvested from human skin, the input voltage from the transducer is as low as 60mV, the proposed circuit, fabricated in a $0.6{\mu}m$ CMOS process, is capable of generating a regulated output voltage of 4.2V with an output power reaching to $40{\mu}W$. The proposed circuit is useful for powering energy to battery-less systems, such as wearable application devices.

• Journal of the Korean Society of Safety
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• v.36 no.5
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• pp.1-9
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• 2021

With the convergence of the information and communication technologies, a new age of technological civilization has arrived. This is the age of intelligent revolution, known as the 4th industrial revolution. The 4th industrial revolution is based on technological innovations, such as robots, big data analysis, artificial intelligence, and unmanned transportation facilities. This revolution would interconnect all the people, things, and economy, and hence will lead to the expansion of the industry. A high-density, high-capacity energy technology is required to maintain this interconnection. As a next-generation energy source, lithium-ion batteries are in the spotlight today. However, lithium-ion batteries can cause thermal runaway and fire because of electrical, thermal, and mechanical abuse. In this study, thermal runaway was induced in 72.5 Ah NCM pouch-type lithium-ion batteries because of thermal abuse. The surface of the pouch-type lithium-ion batteries was heated by the hot plate heating method, and the effect of the rate of increase in the surface temperature on the thermal runaway trigger time was analyzed using Minitab 19, a statistical analysis program. The correlation analysis results confirmed that there existed a strong negative relationship between each variable, while the regression analysis demonstrated that the thermal runaway trigger time of lithium-ion batteries can be predicted from the rate of increase in their surface temperature.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.337-345
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• 2015

After the Fukushima nuclear accident in 2011, concerns about radiation by people are increasing rapidly. If people could know how much they will be exposed by radiation, it may help them avoiding it and understand what exactly radiation is. By doing this, we were helping to reduce the anxiety of radiation contamination. In this study, we have researched figures of radioactivity with 'Captus-3000 thyroid uptake measurement systems' in well counter detector system. The materials were measured with Briquette, Shiitake, Pollock, Button type battery, Alkaline battery, Topsoil, Asphalt, Gasoline, Milk powder, Pine, Basalt stone, Pencil lead, Wasabi, Coarse salt, Tuna(can) Cigar, Beer, and then we categorized those samples into Land resources, Water resources, Foodstuff and Etc (Beer classified as a water resources has been categorized into Foodstuff). Also, we selected the standard radiation source linear 137Cs to measure the sensitivity of well counter detector. After that, we took cpm(counter per minute) for the well counter detector of thyroid uptake system's sensitivity. Then we compared the results of each material's cpm and converted those results to Bq/kg unit. There were a little limitation with the measurement equipment because it has less sensitivity than other professional equipment like 'High purity germanium radiation detector'. Moreover, We didn't have many choices to decide the materials. As a result, there are macroscopic differences among the rates of material's spectrum. Therefore, it had meaningful results that showed how much each material had emitted radiation. To compare the material's cpm with BKG, we've compounded their spectrums. By doing that, we were able to detect some differences among the spectrums at specific peak section. Lastly, Button type battery, Alkaline Battery, Briquette, Asphalt and Topsoil showed high value. There were classified emitting high radiation Group A and emitted lower radiation Group B. The Group A, alkaline battery showed higher rate of radiation by 7.67 %, and Button type battery was yield 4.65 % higher rate than BKG. Additionally, Asphalt (8.03 %), Topsoil (3.76 %), Briquette (7.46 %) were yield for higher values. Several samples of the daily supplies were yield little higher, but it seems safe to use in daily lives. In the case of the 'Foodstuff', all of the samples were safe and they were under the radiation limits of the Ministry of Food and Drug Safety for Food; thus, we highly recommend this study to you as a reference of common daily routine.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.193-198
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• 2012

The following results are from the test of semi-gel electrolyte to store energy efficiently and use advanced VRLA batteries by photovoltaic and wind power generation. Semi-Gel electrolyte with Silica 5% became Gel after 1 and half hour. It shows it is the most suitable time that the electrolyte can be absorbed into the separator and active material of plate to be gel. The test also says that semi-gel electrolyte shows the much better performance for low-rate discharge and the liquid electrolyte is good for high-rate discharge because the reaction rate of gel electrolyte is slower than liquid one for high-rate discharge performance. The test with DOD10% and DOD100% says that 5% silica electrolyte shows much better performance for life efficiency than liquid one. Because semi-gel electrolyte increase the efficiency of gas recombination at the chemical reaction of VRLA battery and it makes minimizing the reduction of electrolyte. Using the 5% silica electrolyte in order to improve the stroage efficiency and life performance for photovoltic and wind power generation, it causes improving by 4.8% for DOD100% and 20% for DOD10%.