• 동력기계공학회지
• /
• 제15권4호
• /
• pp.5-10
• /
• 2011

In case of using rapid vacuum-freeze drying for high quality dry flower of flowering plant, the morphological and physiological characteristics of dry rose showed as the following. The dry ratio of about 82% presented after 1 day in case of using rapid vacuum-freeze drying and it was reached that the optimum storage water content of general dry products was 18%. The dry ratio of about 89% presented after 4 days. This result indicates very short dry time comparing with natural dry time of 12 days. Also, the morphological characteristics of flowering plant in case of vacuum-freeze drying showed similar shape with real flower. The contraction decreased about 9% comparing with real flower under dry time of 72 hours. But the contraction in case of natural dry decreased 36% and showed noticeable difference. The brightness which affects physiological characteristics of dry flowering plant showed lower values according to the dry process and chromaticity was thick. After 4 days, natural dry was thick with about 2 times comparing with vacuum-freeze drying. In case of vacuum-freeze drying, the quantity of anthocyanin and chlorophyl which affect discoloration and bleaching of dry flowering plant showed the clear difference comparing with natural dry method due to the sublimation by vacuum after rapid freeze with short initial time.

• 한국진공학회지
• /
• 제19권4호
• /
• pp.265-274
• /
• 2010

반도체소자 및 디스플레이 제조공정의 핵심 환경인 진공을 형성 유지하기 위한 건식진공펌프는 높은 성능과 신뢰성을 필요로 한다. 건식진공펌프의 개발을 위해서는 다양한 고려와 세밀한 기술적 검토가 필요하다. 본고에서는 반도체 및 디스플레이 제조 공정용 건식진공펌프 개발 과정을 단계별로 소개하고 향후 기술발전 방향에 대해 소개하고자 한다.

• 한국진공학회지
• /
• 제17권4호
• /
• pp.292-301
• /
• 2008

반도체 및 디스플레이 공정과 같이 진공의 높은 청결도의 진공이 필수적으로 요구되어 지는 산업분야가 확대됨에 따라 건식진공펌프의 중요성은 급격히 증대되어 왔다. 다단루츠형 진공펌프와 함께 건식진공펌프 양대 축의 하나를 형성하는 스크류형 건식진공펌프는 공정부산물 발생이 많은 고 난이도 응용분야에서 그 장점을 발휘하여 왔다. 최근 들어 에너지 효율이 획기적으로 개선된 스크류형 건식진공펌프의 개발이 활발히 진행되고 있다. 이 총설논문에서는 스크류형 건식진공펌프의 전반적 기술사항들을 살펴보고 실제 반도체 공정에의 응용 및 스크류형 건식진공펌프의 향후 발전 방향에 대하여 살펴보았다.

• 진공이야기
• /
• 제2권1호
• /
• pp.31-34
• /
• 2015

This article introduces fundamentals of self-diagnosis and predictive (or preventive) maintenance technologies for dry vacuum pumps. The state variables of dry pumps are addressed, such as the pump and motor body temperatures, consumption currents of main and booster pumps, mechanical vibration, and exhaust pressure, etc. The adaptive parametric models of the state variables of the dry pump are exploited to provide dramatic reduction of data size and computation time for self-diagnosis. Two indicators, the Hotelling's $T^2$ and the sum of squares residuals (Q), are illustrated to be quite effective and successful in diagnosing dry pumps used in the semiconductor processes.

• 한국식품저장유통학회지
• /
• 제16권6호
• /
• pp.869-874
• /
• 2009

새로운 돔배기 절임공정을 개발하고자 상압과 감압하에 직간법과 물간법으로 염절임한 돔배기의 품질특성을 비교하였다. 무게 감소율은 물간법으로 상압하에서 절임 하였을 때 12.23%로 높았으며, 수분함량은 감압상태에서 물간법으로 절임한 돔배기가 65.46%로 높았다. 염함량은 직간법으로 감압상태에서 절임 하였을 때 3.02%로 높았으며, 보수력은 직간법으로 감압상태에서 절임한 돔배기가 60.2%로 높았다. 수분활성도는 상압상태에서 직간법으로 절임 하였을 때 0.926으로 낮았으며, 색차는 감압상태에서 물간법으로 절임한 돔배기가 9.75로 가장 낮았으며, 탄력성은 직간법으로 감압상태에서 절임한 돔배기가 91.7%로 높았다. 상압과 감압상태에서 절임한 돔배기을 비교하였을 때, 감압상태에서 절임한 돔배기의 품질특성이 더 좋은 것으로 나타났다. 따라서 감압상태에서의 절임법은 새로운 절임 가공 기술로 활용할 수 있는 가능성을 보였다.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.1313-1316
• /
• 2006

Demands of high volume dry vacuum pumps on the domestic semiconductor and LCD industries are rapidly increasing as the size of wafers and LCD is increasing. This study introduces a new experimental setup for testing the reliability of vacuum pumps. The test system was designed to measure the acoustic pressure and mechanical vibration levels simultaneously. It is shown that the test system enables the analysis and evaluation of the performance of dry pumps under the different gas-load conditions. Detailed experimental result are shown to enable us to examine the characteristics and performance of dry pumps.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2010년도 제39회 하계학술대회 초록집
• /
• pp.17-17
• /
• 2010

This paper address technical issues in calibrating discharge coefficients of sonic nozzles used to measure the volume flow rate of low vacuum dry pumps. The first challenging issue comes from the technical limit that their calibration results available from the flow measurement standard laboratories do not fully cover the low vacuum measurement range although the use of sonic nozzles for precision measurement of gas flow has been well established in NMIs. The second is to make an ultra low flow sonic nozzlesufficient to measure the throughput range of 0.01 mbar-l/s. Those small-sized sonic nozzles do not only achieve the noble stability and repeatability of gas flow but also minimize effects of the fluctuation of down stream pressures for the measurement of the volume flow rate of vacuum pumps. These distinctive properties of sonic nozzles are exploited to measure the pumping speed of low vacuum dry pumps widely used in the vacuum-related academic and industrial sectors. Sonic nozzles have been standard devices for measurement of steady state gas flow, as recommended in ISO 9300. This paper introduces two small-sized sonic nozzles of diameter 0.03 mm and 0.2 mm precisely machined according to ISO 9300. The constant volume flow meter (CVFM) readily set up in the Vacuum center of KRISS was used to calibrate the discharge coefficients of the machined nozzles. The calibration results were shown to determine them within the 3% measurement uncertainty. Calibrated sonic nozzles were found to be applicable for precision measurement of steady state gas flow in the vacuum process. Both calibrated sonic nozzles are demonstrated to provide the precision measurement of the volume flow rate of the dry vacuum pump within one percent difference in reference to CVFM. Calibrated sonic nozzles are applied to a new 'in-situ and in-field' equipment designed to measure the volume flow rate of low vacuum dry pumps in the semiconductor and flat display processes.

• 한국기계가공학회지
• /
• 제14권2호
• /
• pp.67-74
• /
• 2015

In this study, analysis and experiments were carried out on temperature distributions and thermal deformations in a dry vacuum pump with vertical screws for safe operation. When a vacuum pump is working, it is necessary to get rid of the heat generated by the friction of bearings and the compression of air to prevent the vacuum pump from being damaged by interference between two screws and housing through thermal deformation. Additional cooling was proposed by using oil flow through the inner channel of the rotating axis for lower temperature control of the vacuum pump. Analysis and experimental results were compared in terms of temperature distribution and thermal deformation of the vacuum pump, and two sets of results matched reasonably well. These results for a dry vacuum pump with vertical screws can be used in similar model development and can minimize errors in design and manufacture by providing reasonably accurate prediction in advance.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 1998년도 제16회 학술발표회 논문개요집
• /
• pp.148-148
• /
• 1998

• 한국식품저장유통학회지
• /
• 제4권3호
• /
• pp.265-270
• /
• 1997

Effect of modified atmosphere packaging conditions on quality changes of dry jujube was investigated. Dry jujubes with moisture content of 26.7% were packaged in PET/Al/PE film pouches with modified atmospheres. The tested packages include those with normal air, vacuum, CO2 flushing, N2 flushing and O2 scavenger. Packages were stored at 25$^{\circ}C$ for 6 months, during which ascorbic acid concentration, browning level, titratable acidity and surface color were measured. Generally modified atmosphere packages could improve quality retention of dry jujubes except that vacuum package resulted in large surface color change. CO2-flushed package showed the best quality retention of high ascorbic acid content and low browning during 112 days, but caused high amounts of ascorbic acid destruction and browning in longer storage. In all the modified atmosphere packages titratable acidity reached a maximum followed by decline and subsequent rise, while it increased linearly with time in normal air package. Considering ascorbic acid retention browning level and surface color changes during 112 days, the packages of CO2 flushing and N2 flushing were better than others.