• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
• /
• pp.289-294
• /
• 1988

This paper describes tbe design and implementation of the adaptive controller to maintain the glood weld quality in gas metal arc welding process. The weld torch travel speed and the surface temperature are taken, respectively, as an input and an output of the welding control system. Because of the very complex phenomena of the process, the input-output dynamic model was experimentally identified by AIC (Akiake Information Criterion). Based on the model structure, the explicit model reference adaptive controller is simulated in order to regulate the output tempernture to the desired level.

• 한국조명전기설비학회:학술대회논문집
• /
• 한국조명전기설비학회 1999년도 학술대회논문집-국제 전기방전 및 플라즈마 심포지엄 Proceedings of 1999 KIIEE Annual Conference-International Symposium of Electrical Discharge and Plasma
• /
• pp.168-171
• /
• 1999

This paper describes the influence of conducting particle within the coaxial cylindrical electrodes gap under alternating voltage condition investigated using charge simulation method. If the conducting particles precent in the gas insulated system, they can cause decrement of breakdown voltage. Thus, three dimensions computations of electric fields and electrostatic forces have been carried out according to particle location. The results show a good agreement with those of outside country, which can offer a practical reference on the insulation design of domestic GIS.

• 한국산학기술학회논문지
• /
• 제19권3호
• /
• pp.624-629
• /
• 2018

본 논문은 NDIR(Non Dispersive Infra Red) 방식을 적용하여 $CO_2$ 및 $CH_4$의 두 가지 가스를 하나의 휴대용 장치에서 측정이 가능하도록 제작된 복합 가스 측정 장치에 대한 연구이다. 측정 장치의 구성은 적외선램프에서 적외선이 방출되면 방출된 파장이 광학창을 거치면서 흡수로 인하여 빛이 줄어들게 되고 이 감소량(흡수도)을 검출기에서 검출하고 이를 전기적 신호로 변환 증폭하여(3.5V~6V) 정확한 측정이 가능함을 보여준다. 기존의 Single Sensor 방식은 적외선에서 특수파장을 흡수하여 상대 측정량을 검출하는 방식으로 가스의 경우 $4.26{\mu}m$파장의 빛만을 검출하여 측정하는 방식으로 센서의 값을 보정할 수 있는 기준센서가 없어 오차가 발생하는 문제가 발생하였다. 본 연구에 적용된 Dual Sensor 방식은 다른 가스의 영향을 받지 않는 $3.91{\mu}m$의 기준치와 가스의 $4.26{\mu}m$의 두 파장을 검출하여 비교측정 함으로써 오차가 적어 신뢰도가 높은 방식으로, 휴대형으로 소형화하여 저 전력화가 가능하며, $CO_2$ 및 $CH_4$의 2가지 가스농도를 복합적으로 측정 할 수 있다는 특징이 있다. 측정 범위는 $CO_2$의 경우 0ppm~5,000ppm이고 $CH_4$의 경우는 0~5%의 부피 농도로 실내 공기량 1,000ppm을 측정 할 수 있도록 제작되어 휴대용이나 주택의 Home automation과 연동하여 소화연동이 가능함으로 화재예방에 매우 효과적일 것으로 확인하였다.

• 한국안전학회지
• /
• 제14권3호
• /
• pp.93-100
• /
• 1999

Decomposition efficiency, power consumption, and applied voltage of CFC(Chlorofluorocatbon) were investigated by SPCP(surface induced discharge plasma chemical processing) reactor to obtain optimum process variables and maximum decomposition efficiencies. Decomposition efficiency of CFC-12 with various electric frequencies(5~50kHz). flow rates (100~1,000mL/min), initial concentrations(100~1,000ppm), electrode materials(W, Cu, Al). electrode thickness(1, 2, 3mm) and reference gases($N_2$, $O_2$, air) were measured and the products were analyzed with FT-IR. Experimental results showed that at the frequency of 10kHz, the highest decomposition efficiency of 92.7% for CFC-12 were observed at the power consumptions of 29.6W. respectively, and that decomposition efficiency decreased with increasing frequency above 20kHz and decomposition efficiency per unit power were 3.13%/W for CFC-12. Decomposition efficiency was increased with increasing residence times and with decreasing initial concentration of pollutants. Decomposition efficiency was increased with increasing thickness of discharge electrode and the highest decomposition efficiency was obtained for the electrode diameter of 3m. As the electrode material, decomposition efficiency was in order that tungsten(W), copper(Cu), aluminum (Al). Decomposition of CFC-12 in the reference gas of $N_2$ showed the highest efficiency among three reference gases, and then the effect of reference gas on the decomposition efficiency decreased in order of air and $O_2$. The optimum power for the maximum decomposition efficiency was 25.3W for CFC.

• 한국화재조사학회논문지
• /
• 제11권1호
• /
• pp.59-65
• /
• 2008

각종 화재사고 분류 중 대표적으로 나타나는 가스사고는 그 형태와 원인이 다양하다고 할 수 있다. 가스사용량은 사용가구수가 증가와 사용 장소 및 가스기기의 다양화로 증가하고 있으며, 2007년도 가스사용량은 35,078천톤으로서 연평균 9.4%증가하였다. 가스사고는 95년 557건을 최고로 하여 2007년도에는 123건 발생하여 연평균 11.5%감소되었다. 가스의 종류에 따른 사고건수는 LP가스의 경우 전체 가스사고중 약 80%를 차지하고, 도시가스와 고압가스가 약 20%를 차지하고 있다. LP가 많았고, 특히 공급자부주의에 의한 사고가 끊이지 않고 증가하고 있는 추세이다. 가스사고는 사용자취급부주의, 공급자 취급부주의, 시공불량 및 노후제품으로부터 사고가 발생하여 인명과 재산피해가 발생하고 있다. 본 논문에서는 가스사고의 분류와 형태별, 원인별, 지역별 등에 대한 사고분포를 통해 가스사고의 원인에 대한 이해를 하고 가스안전사고를 예방하는 자료로 활용되도록 하였다.

• 한국유체기계학회 논문집
• /
• 제15권3호
• /
• pp.51-56
• /
• 2012

This study analyzed the influence of firing biogas on the performance and operation of a gas/steam turbine combined system. A reference gas/steam turbine combined system, designed with biogas fuel(57% volumetric methane) was set up and off-design simulation was made to investigate operating characteristics when a couple of operating schemes to mitigate turbine blade overheating were applied. Performance at base-load operation using each scheme was compared and part load operation using the variable inlet guide vane was analysed. Also, differences in operating characteristics and performance caused by changes in the methane content of biogas and ambient temperature were examined.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 2008년도 춘계학술대회 논문집
• /
• pp.1114-1118
• /
• 2008

In previous fire accident of railway car, the fatality was relatively high by toxic gas poisoning cause of closed space. So the necessity of quantifying toxic gas in combustion gas was recognized and then, FT-IR spectroscopy was introduced for real-time analysis of mixed gases and stimulated analysis of the concentration of several gases. Thus, in this study, absorption bands using FT-IR were obtained by each component of combustion gases for interior materials of railway car such as flooring materials and moquette seat. And then the sample spectra were compared with the spectra of NO, $NO_2$, $SO_2$ reference gases, we could obtain some identical peaks of them.

• 한국입자에어로졸학회지
• /
• 제14권2호
• /
• pp.41-47
• /
• 2018

Numerical analysis was conducted to characterize particle deposition onto a heated horizontal semiconductor wafer in vacuum environment. In order to calculate the properties of gas surrounding the wafer, the gas was assumed to obey the ideal gas law. Particle transport mechanisms considered in the present study were convection, Brownian diffusion, gravitational settling and thermophoresis. Averaged particle deposition velocities on the upper surface of the wafer were calculated with respect to particle size, based on the numerical results from the particle concentration equation in the Eulerian frame of reference. The deposition velocities were obtained for system pressures of 1000 Pa~1 atm, wafer heating of 0~5 K and particle sizes of $2{\sim}10^4nm$. The present numerical results showed good agreement with the available experimental ones.

• Structural Engineering and Mechanics
• /
• 제33권3호
• /
• pp.339-355
• /
• 2009

The sealed, tuned liquid column gas damper (TLCGD) with gas-spring effect extends the frequency range of application up to about 5 Hz and efficiently increases the modal structural damping. In this paper the influence of several TLCGDs to reduce coupled translational and rotational vibrations of plan-asymmetric buildings under wind or seismic loads is investigated. The locations of the modal centers of velocity of rigidly assumed floors are crucial to select the design and the optimal position of the liquid absorbers. TLCGD's dynamics can be derived in detail using the extended non-stationary Bernoulli's equation for moving reference systems. Modal tuning of the TLCGD renders the optimal parameters by means of a geometrical transformation and in analogy to the classical tuned mass damper (TMD). Subsequently, fine-tuning is conveniently performed in the state space domain. Numerical simulations illustrate a significant reduction of the vibrations of plan-asymmetric buildings by the proposed TLCGDs.

• 천문학회보
• /
• 제43권2호
• /
• pp.55.1-55.1
• /
• 2018

Theoretical models of reionization require that approximately 10% of the Lyman Continumm (LyC) photons escape from their host dark matter haloes and re-ionize neutral hydrogen in the Universe. However, observations of Lyman break galaxies (LBGs) at z~3 report much lower escape fractions of $f_{esc}{\sim}1%$. In an attempt to understand the discrepancy, we perform radiation-hydrodynamics simulations of isolated disk galaxies using RAMSES-RT with high resolution (maximum ~ 9 pc). We find that $f_{esc}$ is ~6% on average for the reference run ($Z=0.1Z{\odot}$), whereas the fraction decreases to ~1% in the case of metal-rich disk ($Z=1Z{\odot}$). This happens because dense metal-poor gas clumps are disrupted early due to strong Lya pressure and supernova explosions, while star particles are trapped for a longer period of time in the metal-rich environments. We also find that $f_{esc}$ is still significant (~4%) even when the amount of metal-poor gas is increased by a factor of 5. Our preliminary results suggest that the low escape fractions in LBGs may be better explained by (locally) metal-enriched gas near young stars than high gas fractions in galaxies.