• 센서학회지
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• 제19권4호
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• pp.313-319
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• 2010

Vibration energy harvesting is an attractive technique for potential powering of low power devices such as wireless sensors and portable electronic applications. Most energy generator developed to date are single vibration frequency based, and while some efforts have been made to broaden the frequency range of energy harvester. In this work, The effect of energy harvesting were investigated at various vibration frequencies, vibration beams, vibration point and test masses. The maximum output voltage of the bimorph piezoelectric cantilever was shifted according to vibration point. Vibration frequency with maximum output voltage decreased with the increasing length of vibration beam and increasing test mass. The sample with vibration beam length 0.5 L generated a peak output voltage of 32 $V_{rms}$ and shows a 45 % increase in voltage output in comparison to the corresponding original bimorph. It was found that a piezoelectric bimorph has a possibility to be as the energy harvesting cantilever, which is successfully tuned over a vibration frequency range to enable a maximum harvesting energy.

• 한국융합학회논문지
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• 제11권4호
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• pp.55-61
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• 2020

다양한 종류의 방사선 발생장치가 동물병원에서 사용되면서 방사선 관계종사자들의 안전이 중요해지고 있으나 방사선 발생장치 및 방사선 관계종사자들에 대한 안전관리 정보가 없는 실정이다. 이에 본 연구에서는 방사선 검사기관 및 측정기관, 시·군·구에서 조사되어진 방사선 발생장치 및 관계종사자, 피폭선량 등을 조사, 분석하였다. 최근 6년간 동물병원에서의 방사선 발생장치와 관계종사자 수는 각각 2,138대에서 2,972대, 2,644명에서 5,733명으로 증가하였다. 2019년 방사선 발생장치의 수는 일반 X-ray, CT, C-arm, 이동형 X-ray, 치과용 X-ray는 각각 2,204대, 58대, 67대, 770대, 14대인 것으로 조사되었다. 2019년 방사선 관계종사자 수는 수의사 4,236명, 수의간호사 1,080명, 업무보조원 404명, 기타 13명인 것으로 조사되었다. 2018년 방사선 관계종사자 연간평균피폭선량은 표층선량 0.21mSv, 심부선량 0.18mSv인 것으로 나타났다. 본 연구는 동물병원에서 사용하고 있는 방사선 발생장치 및 방사선 관계종사자의 안전관리에 대한 기초 자료가 될 것으로 기대한다.

• 대한기계학회논문집B
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• 제37권1호
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• pp.81-86
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• 2013

소형디젤 발전기의 배기가스는 양적 및 질적 수준에서 유용하게 활용되기에는 부족한 폐열원으로 간주된다. 그러나 본 연구에서는 이러한 배기가스의 폐열을 히트파이프에 의해 회수하고 다중효용확산 증발에 의해 효율적으로 열을 이용하는 해수담수기를 제안하였다. 제안한 증류기는 $171^{\circ}C$의 배기가스에서 52 W 의 폐열을 회수할 수 있고, 이 회수 열량 중 약 85%가 약 70 g/h의 담수를 생산할 수 있는 유용한 열량으로 사용된다. 이 결과는 50cc, 4 행정 엔진을 가진 극소형 발전기의 폐열에 대하여 단효용 장치의 실험값이므로, 10 중효용으로 구성할 경우 약 500 g/h 의 성능을 가질 수 있는 것으로 계산되었다. 따라서 본 증류기는 전기와 담수가 동시에 부족한 지역에서 실제 필요한 식수량을 확보할 수 있는 소용량 담수화장치로 유용하게 활용될 수 있다.

• 센서학회지
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• 제14권1호
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• pp.33-41
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• 2005

For more convenient electrode-electrolyte interface impedance analysis in biosensor, a stand-alone impedance measurement system is required. In our study, we developed a PC-based portable system to analyze impedance of the electrochemical cell using microprocessor. The devised system consists of signal generator, programmable amplifiers, A/D converter, low pass filter, potentiostat, I/V converter, microprocessor, and PC interface. As a microprocessor, PIC16F877 which has the processing speed of 5 MIPS was used. For data acquisition, the sampling rate at 40 k samples/sec, resolution of 12 bit is used. RS-232 with 115.2 kbps speed is used for the PC communication. The square wave was used as stimuli signal for impedance analysis and voltage-controlled current measurement method of three-electrode-method were adopted. Acquired voltage and current data are calculated to multifrequency impedance signal after Fourier transform. To evaluate the implemented system, we set up the dummy cell as equivalent circuit of which was composed of resistor, parallel circuit of capacitor and resistor connected in parallel and measured the impedance of the dummy cell; the result showed that there exist accuracy within 5 % errors and reproduction within 1 % errors compared to output of Hioki LCR tester and HP impedance analyzer as a standard product. These results imply that it is possible to analyze electrode-electrolyte interface impedance quantitatively in biosensor and to implement the more portable high speed impedance analysis system compared to existing systems.

• 한국안전학회지
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• 제27권5호
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• pp.224-228
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• 2012

According to the results of Probabilistic Safety Assessment(PSA) for a Nuclear Power Plant(NPP), an Emergency Power Supply(EPS) system has been considered as one of the most important safety system. Especially, the interests in the reliability of the EPS system have been increased after the severe accidents of Fukushima Daiichi. Firstly, we performed the risk assessment and the importance analysis of the EPS system based on the PSA models of the reference plant, which is the Korean standard NPP type. Considering a portable Diesel Generator(DG) system as the reliability reinforcement of the EPS system, we modified the PSA models and performed the risk impact assessment and the importance analysis. Although the reliability of the potable DG could be about 20% of the reliability of the alternative AC DG, we identified that Core Damage Frequency(CDF) was decreased by at least 4.6%. In addition, the risk impacts due to the unavailability of the EPS system on CDF were decreased.

• 수산해양기술연구
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• 제50권1호
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• pp.50-57
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• 2014

The performance of five kind adsorbents, which can reduce nitrogen oxide (NOx) from the diesel engine occupying 85% of the fishing boat, was carried out and the emission reduction filter was manufactured and evaluated in the adsorption efficiency of the emission gas for 240 KW diesel portable generator. As a NOx emission filter made of mordenite which has an excellent cation exchange capacity was manufactured by ball type adsorbents having excellent specific surface area. The adsorption efficiency of mordenite material applying the emission reduction filter began to show up at the operating time 10 minutes in comparison with the activated carbon and zeolite materials, and it was exposed to continue until 100% capability with passing by 20 minutes. So the adsorption efficiency of the NOx reduction filter consistently maintained at the averaged 80%.

• ETRI Journal
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• 제28권5호
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• pp.583-592
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• 2006

Digital broadcasting technology has developed focusing on multi-channel/multi-media, high-definition quality, and mobility-support. Recently, there has been a clear trend toward bidirectional service with the convergence between broadcasting and communication. The broadcasting viewer is no longer simply a passive receptor but has also become an information generator. Currently, the digital multimedia broadcasting (DMB) specifications are the major standard for portable digital broadcasting and have been establishing the overall guidelines for bidirectional service using the MPEG-4 system. While detailed specifications for DMB systems are not well-established for bidirectional service yet, they share the basic concepts underlying the European Eureka-147 Digital Audio Broadcasting (DAB) system. This paper develops key scenarios for bidirectional service in DMB, describes the signal transaction of broadcasting and return channels, and demonstrates typical scenarios using binary format for scenes (BIFS) in the MPEG-4 system.

• 방사선산업학회지
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• 제4권1호
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• pp.79-83
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• 2010

The pollutants in subsurface soil are advected by groundwater flow and transported by the hydrodynamic dispersion. In this study, laboratory-scale experiments by using a radioisotope were conducted to evaluate the characteristics of the transport and dispersion of pollutants in the soil. The hydraulic model of the laboratory-scale was manufactured based upon its geometric similarity. Tc-99m having a short half-life was used with a tracer and it was injected instantaneously into the soil. Tc-99m milked from a $^{99}Mo/^{99m}Tc$ portable generator fabricated for medical purposes had 0.141 MeV of gamma radiation. The experiments are performed by the different conditions like the variations of groundwater velocity and the results are analyzed by the measured CPS of Tc-99m.

• 한국산업보건학회지
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• 제15권3호
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• pp.183-191
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• 2005

This study is designed to compare the performance of established samplers (personal air sampler and MiniVOL portable air sampler) commonly used in the air environment or work environment with that of the sampler made by remodeling the air bubble generator for aquarium fishes. Sampling method used in this study is the filter collection method for PM10 and total suspended particles (TSP), the liquid collection method for sulfur dioxide ($SO_2$) and nitrogen dioxide ($NO_2$), and the solid collection method for toluene, respectively. There is not a significant difference in the average concentration of TSP between the Gilian personal air sampler (1st, $0.316{\pm}0.095$; 2nd $0.191{\pm}0.090$; 3rd, $0.185{\pm}0.073mg/m^3$) and the remodeled sampler (1st, $0.317{\pm}0.106$, 2nd $0.201{\pm}0.050$; 3rd $0.189{\pm}0.081mg/m^3$). There are also not significant differences in the average concentration of PM10 among the Gilian personal air sampler ($0.058{\pm}0.006mg/m^3$), the remodeled sampler ($0.052{\pm}0.008mg/m^3$) and the MiniVOL portable air sampler ($0.054{\pm}0.007mg/m^3$). The average concentration of the SO2 by the established sampler and the remodeled one is $3.79{\pm}0.21ppb$ and $3.45{\pm}0.15ppb$, respectively. In addition, there are not sigmficant differences in the average concentration of the NO2 between the Gilian personal air sampler (1st, $0.325{\pm}0.068$; 2nd $0.341{\pm}0.206$; 3rd, $2.971{\pm}0.078{\mu}g/m^3$) and the remodeled sampler (1st, $0.300{\pm}0.062$; 2nd $0.332{\pm}0.144$, 3rd, $2.968{\pm}0.085{\mu}g/m^3$). There are not significant differences in the average concentration of toluene between the Gilian personal air sampler (1st, $0.499{\pm}0.072$; 2nd $0.598{\pm}0.112$; 3rd $2.284{\pm}0.077{\mu}g/m^3$) and the remodeled sampler (1st, $0.463{\pm}0.133$; 2nd $0.603{\pm}0.082$; 3rd $2.353{\pm}0.115{\mu}g/m^3$). From these results, we can conclude that the performance of the remodeled sampler is not different from that of established samplers. There is possibility that the remodeled sampler can be used as a alternative device for Gilian personal air sampler in area and personal air sampling.

• 한국산학기술학회논문지
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• 제15권4호
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• pp.2349-2354
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• 2014

스마트폰 가입자의 지속적인 증가로 인하여 SMART강국으로 도약하고 있으며, 정부 및 대기업에서도 혁명적인 변화가 몰고 있다. 또한 국내뿐만 아니라 국외에서도 스마트폰, 태블릿 PC, 전자북등 다양한 스마트기기가 생산되고 있으며 발전하고 있다. Portable성과 편의성이 강조된 스마트 폰은 기존의 휴대폰처럼 단순 통화, SMS, MMS 기능만이 아닌 언제 어디서나 사람들과 의사소통, 다양한 콘텐츠 제공으로 인한 취미, 여가생활을 제공하고 있다. 하지만 사용자 측면에서 PC의 웹 페이지를 모바일 페이지에 적용하게 되면 화면의 사이즈, 멀티미디어 콘텐츠(SWF, WMF, AVI, MOV)가 정상적으로 재생이 되지 않아 사용자 측면에서 많은 불편을 주고 있다. 따라서 본 논문에서는 스마트기기 환경에서 이차원 바코드인 QR Code를 활용하여 효율적인 모바일 콘텐츠 생성프로그램을 연구하였다. 또한 기존의 획일적인 디자인만 꾸밀 수 있는 QR Code Generator와 달리 사용자 측면에서 독창적인 QR Code 생성 시스템을 구현하였다.