• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.777-780
• /
• 2005

The high vacuum in a electron beam lithography is basic condition, because electron beam vanish by collision with air molecules in generally atmosphere. To make high vacuum state, the vacuum control valve is essential. Most vacuum control valve are manual units. So, user of manual vacuum valve must have understanding vacuum process to change from low vacuum to high vacuum state. The user of electron beam lithography are troubled with operation of manual vacuum valve, in case the vacuum chamber is frequently open. In this paper, the design and performance test of auto vacuum control valve for electron beam lithography are described. With the auto vacuum control valve, the high vacuum level can reach 2.8E-5 Torr.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2003년도 ICCAS
• /
• pp.1537-1541
• /
• 2003

In this paper, presented is a feedback control performance of vibratory gyroscope at various vacuum levels. Micro gyroscope, whose operation is based on the vibrating motion at the vacuum conditions, is highly influenced by the vacuum level of the operating circumstances. In general, we apply the feedback control scheme to the gyroscope in order to improve the performances of the sensor. And control performances of the gyroscope are related to those vacuum levels. So we need investigate the performances of the closed loop control at various vacuum conditions comparing with those of the open loop. The experimental results show that the sensitivity of the closed loop is less than that of the open loop especially in low vacuum conditions. Therefore, there should be trade-off between sensitivity and other sensor performances such as linearity, bandwidth when we apply feedback control to the gyroscope.

• 한국추진공학회:학술대회논문집
• /
• 한국추진공학회 2009년도 춘계학술대회 논문집
• /
• pp.67-70
• /
• 2009

고농도 과산화수소를 이용한 연구가 활발해짐에 따라 과산화수소의 국내 생산을 위한 증류 방법에 대한 연구가 요구된다. 증류 방법에는 증류할 물질의 공급방식과 증류 회수, 증류 압력 등의 증류 조건에 따라 여러 가지 방법이 존재하며 과산화수소 증류에는 진공증류법이 사용된다. 진공 증류는 과산화수소의 열분해와 공기 중 입자와의 반응을 줄일 수 있다. 증류 조건은 Raoult's law를 이용하여 결정하였다. 실험 장치의 낮은 진공도와 진공도의 조절이 중요한 문제로 나타났으나 진공 챔버의 교체로 진공의 누설을 막아 진공도를 높였으며, 실험 장치에 정량밸브를 설치하여 진공도를 조절하였다.

• 항공우주기술
• /
• 제6권1호
• /
• pp.64-73
• /
• 2007

차세대 대형위성에 대한 우주환경모사를 위한 대형열진공챔버가 한국항공우주연구원에 의해 성공적으로 국산화 구축되었다. 유효직경 8미터, 유효깊이 10미터의 대형열진공챔버는 크게 진공계와 열제어계, 방진계로 구분되며, $3.7{\times}10^{-5}Pa$($5{\times}10^{-7}torr$) 이하의 진공 환경에서 액체질소를 이용해 위성을 감싸는 쉬라우드의 온도를 $-190^{\circ}C$ 이하로 유지할 수 있고, $10^{-5}g_{rms}$ 이하의 진동레벨을 갖는 방진시스템을 갖추어 우주환경에서의 광학시험을 가능하게 한다. 또한 챔버내에 설치된 할로겐램프를 이용하여 쉬라우드의 온도를 섭씨 123도까지 상승시켜 베이크아웃 시험을 수행할 수 있으며, PLC(Programmable Logic Controller)를 기반으로 한 제어프로그램을 이용하여 대형열진공챔버의 자동화 제어를 수행할 수 있다.

• 센서학회지
• /
• 제27권5호
• /
• pp.300-305
• /
• 2018

The uncooled microbolometer thermal sensor for low cost and mass volume was designed to target the new infrared market that includes smart device, automotive, energy management, and so on. The microbolometer sensor features 80x60 pixels low-resolution format and enables the use of wafer-level vacuum packaging (WLVP) technology. Read-out IC (ROIC) implements infrared signal detection and offset correction for fixed pattern noise (FPN) using an internal digital to analog convertor (DAC) value control function. A reliable WLVP thermal sensor was obtained with the design of lid wafer, the formation of Au80%wtSn20% eutectic solder, outgassing control and wafer to wafer bonding condition. The measurement of thermal conductance enables us to inspect the internal atmosphere condition of WLVP microbolometer sensor. The difference between the measurement value and design one is $3.6{\times}10-9$ [W/K] which indicates that thermal loss is mainly on account of floating legs. The mean time to failure (MTTF) of a WLVP thermal sensor is estimated to be about 10.2 years with a confidence level of 95 %. Reliability tests such as high temperature/low temperature, bump, vibration, etc. were also conducted. Devices were found to work properly after accelerated stress tests. A thermal camera with visible camera was developed. The thermal camera is available for non-contact temperature measurement providing an image that merged the thermal image and the visible image.

• Food Science and Biotechnology
• /
• 제15권2호
• /
• pp.248-253
• /
• 2006

This study examined the effects of vacuum packaging and modified atmosphere packaging (MAP) on the meat quality of ${\alpha}$-tocopherol supplemented broiler chicks after prolonged refrigeration. The supplemented ${\alpha}$-tocopherol levels had no effect on the body weight and feed efficiency. The dietary treatments and packaging methods had no significant effects on the level of microbial growth, lightness, and the metmyoglobin content. The vacuum packaging showed the highest level of purge loss. The broilers supplemented with either 200 or 400 IU of ${\alpha}$-tocopherol had a lower level of malondialdehyde than the control group. The vacuum packaged meats from chicks fed the control diet showed the highest levels of lipid oxidation. The lipid oxidative stability was most improved in modified atmosphere (20% $CO_2$ + 80% $N_2$) packaged breast meat from the broilers supplemented with either 200 or 400 IU of ${\alpha}$-tocopheryl acetate.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2007년도 추계학술대회논문집
• /
• pp.1297-1301
• /
• 2007

The Conventional noise control attempts to simply reduce the level of product noise. But it is very straight forward way that we have consider human perception on noise. Since human listening is very sensitive to sound. Evaluation of the sound quality of a Vacuum Cleaner is studied base on human sensibility engineering. In this paper, we choose two Vacuum Cleaners that are sold in Korea and reduced noise control. Comparison Method is used to evaluate noise and preference of Vacuum Cleaner by steps. The sound quality of Vacuum Cleaner noise is analyzed by employing the subjective evaluation and by representing them in terms of the objective quantities. Semantic Differential Method is used to study sound quality Evaluation. To analyze the sound quality of Vacuum Cleaner noise, consider the coefficients of correlation between sound metrics and subjective rating. The linear regression models were obtained for the subjective evaluation and sound quality metrics.

• 한국소음진동공학회논문집
• /
• 제20권12호
• /
• pp.1223-1228
• /
• 2010

The conventional noise control attempts to simply reduce the level of product noise. But it is very straight forward way that we have considered human perception on noise. Since human listening is very sensitive to sound. Evaluation of the sound quality of a vacuum cleaner is studied base on human sensibility engineering. In this paper, we choose six vacuum cleaners that are sold in Korea and reduced noise control. The sound quality of vacuum cleaner noise is analyzed by employing the subjective evaluation and by representing them in terms of the objective quantities. Semantic differential method is used to study sound quality Evaluation. To analyze the sound quality of vacuum cleaner noise, consider the coefficients of correlation between sound metrics and subjective rating. The linear regression models were obtained for the subjective evaluation and sound quality metrics.

• 진공이야기
• /
• 제5권1호
• /
• pp.13-17
• /
• 2018

Phase transition is not unique to solid state systems or homogeneous molecular systems but it is also observed in highly heterogeneous biological systems. Phase transition and phase separation in cells are recently being found to be central to many biological functions by temporarily and locally controlling the storage and exchange of certain proteins and RNAs. There are also clues suggesting them to be playing pivotal roles in the spatial organization of chromosomes into topological domains and its time-dependent control. Here we introduce early efforts to explain at the molecular level how the spatiotemporal organization of chromosomes are programmed and modulated by the sequence and chemical modifications of the DNA. Continuing works may provide a physical framework to understand the molecular level control of chromosome structure and dynamics that determine the epigenetic state and the fate of the cells.

• 반도체디스플레이기술학회지
• /
• 제11권2호
• /
• pp.63-69
• /
• 2012

As decreasing size of chips, the need of wafer level packaging is increased in semi-conductor and display industries. Temperature uniformity is a crucial factor in vacuum soldering process to guarantee quality of bonding between chips and wafer. In this paper, a stepwise iterative algorithm has been suggested to obtain output profile of each heat source. Since this algorithm is based on open-loop stepwise iterative experimental technique, it is easier to implement and cost effective than real time feedback controls. Along with some experiments, it was shown that the suggested algorithm can remarkably improve temperature uniformity of wafer during whole heating process compared with the ordinary manual trial-and error method.