• 대한기계학회논문집B
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• 제27권7호
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• pp.877-882
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• 2003

The main objective of the present study is to analyze the heat transfer characteristics in the vacuum carburizing furnace. Local temperatures are measured at different locations in the self-fabricated furnace for various operating conditions using K-type thermocouples. In addition, the present study simulates the fluid flows and heat transfer in the vacuum carburizing furnace using a commercial package (Fluent V. 6.0), and compares the predictions of local temperatures with experimental data. The temperature and flow fields are predicted. It is found that the time taken for reaching the steady-state temperature under the vacuum pressure is shorter than that under the normal pressure condition. It means that the carburizing furnace under vacuum pressure condition is capable of saving the required energy more efficiently than the furnace under the normal pressure condition. Furthermore, the temperature variations predicted by the numerical simulations are in good agreement with experimental data.

• 식품과학과 산업
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• 제50권2호
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• pp.12-26
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• 2017

Processing steps such as washing and cutting, involved in preparing fresh-cut produce causes tissue damage, leading to rapid quality deterioration. Major defects of fresh-cut produce are discoloration, softening, off-odor development, and microbial growth. Packaging of fresh-cut produce has been changed to reduce these quality problems. Flexible packaging film is widely used to pack fresh-cut produce. Vacuum packaging was the popular packaging method in the beginning of fresh-cut industry in Korea. Vacuum packaging creates high $CO_2$ and low $O_2$ levels to control browning of fresh-cut produce. However, these conditions induce some visual defects and off-odor development. Discoloration problem was also found when fresh-cut produce was packaged with conventional packaging film or plastic tray. Modified atmosphere (MA) packaging is effective for prolonging shelf-life of fresh-cut produce by decreasing $O_2$ and increasing $CO_2$ concentration in the package. Retail MA packaging using different oxygen transmission rate (OTR) film and micro-perforated film has started to be applied to fresh-cut produce in Korea. Proper MA package design that provides optimum range of $O_2$ and $CO_2$ partial pressures is one of the major challenges in the industry. An initial package flushing with $N_2$ or an low $O_2$/high $CO_2$ atmosphere is also used to more rapidly establish steady-state MA condition. Film OTR and $O_2$ flushing affects the fermentative volatile production, off-odor development, electrolyte leakage, discoloration, $CO_2$ injury, microbial population of fresh-cut produce. There is also a demand for convenient packaging to attract consumers. Rigid fresh-cut produce container for retail market has increased since the packaging provides excellent protection from physical damage during transport. Rigid tray used as actual serving vessel for the consumer is increasing in Korea. The tray with flexible lid to wrap or seal fresh-cut produce is more and more gaining popularity. Further practical technology to control quality change and microbial growth for each fresh-cut product has been studied since various fresh-cut items were required. The fresh-cut industry also focuses on searching for more convenient and environmentally friendly packaging.

• Journal of Korean Vacuum Science & Technology
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• 제6권3호
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• pp.109-115
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• 2002

This paper describes a CCM key comparison of low absolute-pressure standards at seven National Measurement Institutes that was carried out during the period March 1998 to September 1999 in order to determine their degrees of equivalence at pressures in the range 1 Pa to 1000 Pa. The Korea Research Institutes of Standards and Science(KRISS) participated from 10 Pa to 1000 Pa pressure range in 1999. The primary standards, which represent two principal measurement methods, included five liquid-column manometers and four static expansion systems. The transfer standard package consisted of four high-precision pressure transducers, two capacitance diaphragm gauges to provide high resolution at low pressures, and two resonant silicon gauges to provide the required calibration stability.

• 한국축산식품학회지
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• 제18권2호
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• pp.115-124
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• 1998

This study was carried out investigate hygienic conditions of domestic packing plant for export and the shelf-life by Japanese standards. vacuum packaged chilled port loins provided by five packers(A, B, C, D and E) were transported to Japan in the same condition, Four packers(A, B, C adn d) produced the samples as hygienic as possible and one packer produced loins in the traditional hygienic condition, In TTC(2,3,5-triphenyl tetrazolium chloride) test all samples showed the negative reaction from the date of the quarantine(14 days after slaughtering) to 50 days The numbers of total plate count(TPC) of A, B, C and D packers that were below 108CFU/g until 50 days were accepted by Japanese Standards but TPC of E packer was over 107CFU/g at 30 days. VBN values increased sig-nificantly(P<0.01) in samples of A,B and D packers in the samples of C packer and E packer at 5% and 0.1% level respectively. The pH values of the vacuum packaged chilled pork for export at 14 days after slaughtering were 5.43∼6.00 In sensory evaluation, A, B, C and D packers which improved hygi-enic condition produced the products with good color and appearance. low drip until 40 days storage at $0^{\circ}C$ But as the storage time increase off-flavor occured at 40days in A and D packer and at 50days in B and C packer. In conclusion according to the above results of microbiological physicochemical and sensory evalution the edible periods of Korean vacuum package chilled porks may be estimated to 40∼50 days for the packers who improved hygienic condition and the shelf lives were calculated as 32∼40 days from edible period by a factor of 0.8(safety coefficient) while that of the pork from E packer which was produced in the traditional hygienic condition was estimated to 30 days after slaughtering at $0^{\circ}C$ Therefore the shelf-life of the pork of E packer would be only 24 days.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.632-639
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• 2014

Mechanical stress and the vacuum level are the two main factors dominating the quality factor of a resonator operated in the vacuum range 1 mTorr to 10 Torr. This means that if the quality factor of a resonator is very insensitive to the mechanical stress in the vacuum range, it is sensitive to mainly the ambient vacuum level. In this paper, a wafer-level packaged MEMS resonator with a highly vacuum-sensitive quality factor is presented. The proposed device is characterized by a package with out-of-plane symmetry and a suspending structure with only a single anchor. Out-of-plane symmetry helps prevent deformation of the packaged device due to thermal mismatch, and a single-clamped structure facilitates constraint-free displacement. As a result, the proposed device is very insensitive to mechanical stress and is sensitive to mainly the ambient vacuum level. The average quality factors of the devices packaged under pressures of 50, 100, and 200 mTorr were 4987, 3415, and 2127, respectively. The results demonstrated the high controllability of the quality factor by vacuum adjustment. The mechanical robustness of the quality factor was confirmed by comparing the quality factors before and after high-temperature storage. Furthermore, through more than 50 days of monitoring, the stability of the quality factor was also certified.

• 한국진공학회지
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• 제18권5호
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• pp.337-345
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• 2009

패키지 기판의 지름 $100{\mu}m$ 이하 미세 드릴 구멍의 경우 습식 디스미어 공정만으로는 구멍 내부의 스미어를 효과적으로 제거할 수 없다. 본 연구에서는 습식 디스미어 공정의 이전 단계에서 대기압 플라즈마를 처리하여 소수성의 기판 표면을 친수성으로 개질하고자 하였다. 대기압 플라즈마 공정은 리모트 DBD 방식의 전극을 이용하여 패키지 제조 공정에 적합한 인라인 형태의 장비로 구성되었다. 대기압 플라즈마를 처리한 결과 접촉각 기준으로 $71^{\circ}$의 소수성 절연 필름 표면이 $30^{\circ}$ 정도의 친수성 표면으로 개질되었다. 대기압 플라즈마 처리 유무에 따른 습식 디스미어 공정의 특성을 평가하기 위하여 절연 필름의 두께, 드릴 구멍 지름, 표면 조도의 변화를 측정하였는데, 대기압 플라즈마 처리 시 기판 전면에서 공정 특성의 균일도가 향상되는 것을 확인하였다. 또한 대기압 플라즈마 처리 유무에 따른 드릴 구멍의 SEM 사진 분석 결과 대기압 플라즈마 처리 시 구멍 내부의 스미어가 효과적으로 제거됨을 실험적으로 확인하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2500-2505
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• 2007

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compact and environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the electromagnetic behaviors of high-current vacuum arcs for two different types of AMF contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• 대한기계학회논문집A
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• 제32권1호
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• pp.7-12
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• 2008

The vacuum interrupter (VI) is used for medium-voltage switching circuits due to its abilities and advantages as a compacted environmental friendly circuit breaker. In general, the application of a sufficiently strong axial magnetic field (AMF) permits the arc to be maintained in a diffused mode to a high-current vacuum arc. A full understanding of the vacuum arc physics is very important since it can aid to improve the performance of vacuum interrupter. In order to closely examine the vacuum arc phenomena, it is necessary to predict the magnetohydrodynamic (MHD) characteristics by the multidisciplinary numerical modeling, which is coupled with the electromagnetic and hydrodynamic fields, simultaneously. In this study, we have investigated the effect of changing geometrical parameters for electromagnetic behaviors of high-current vacuum arcs with two different types of AMP contacts, which are coil-type and cup-type, using a commercial finite element analysis (FEA) package, ANSYS. The present results are compared with those of MAXWELL 3D, a reliable electromagnetic analysis software, for verification.

• 한국진공학회지
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• 제10권1호
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• pp.9-15
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• 2001

질량분석기가 장착된 초고진공챔버를 사용하여 미소체적을 갖는 평판표시소자용 패널내부에 존재하는 잔류가스의 전체압력과 분압을 성공적으로 측정하였다. 패널내부의 전체압력은 $10^{-6}$Torr범위로 측정되었으며, 전체압력의 증가에 크게 기여하는 가스분압은 아르곤, 메탄 및 헬륨 분압들이었다. 패널의 진공패키징을 위한 배기공정시 가열온도는 고진공패키징에 있어서 매우 중요하며, 가열배기 온도가 높을수록 전체압력과 메탄분압은 감소하였다.

• 마이크로전자및패키징학회지
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• 제10권1호
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• pp.31-38
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• 2003

MEMS 소자는 현재의 전자산업환경에서 여러 요구조건을 만족시킬 수 있는 특징을 갖추고 있으며 이러한 MEMS 소자를 이용한 MEMS 구조물의 packaging 방법에 있어서는 내부 MEMS 소자의 동작을 위한 외부 환경으로부터의 보호를 위하여 Hermetic sealing에 대한 요구를 충분히 만족시켜야 한다. 본 논문에서는 이와 같은 MEMS device의 진공 패키지를 구현함에 있어서 기판내부에 수동소자를 실장할 수 있는 LTCC 기술$^{1)}$ 을 이용하여 진공 패키징하는 방법에 대하여 소개한다. 본 기술을 이용하는 경우 기존의 Hermetic sealing이외에 향후 적층 기판 내부에 수동소자를 내장시켜 배선 길이 및 노이즈 성분을 감소시켜 더욱 전기적 성능을 향상시킬 수 있는 장점이 있게된다. 본 논문에서는 LTCC기판을 이용하여 패키징 시킨 후, 내부 진공도에 영향을 줄 수 있는 계면들에서의 시간에 따른 진공도 변화로부터 leakage rate를 측정 (stacked via : $4.1{\pm}1.11{\times}10^{-12}$/Torr1/sec, LTCC 기판/AgPd/solder/Cu의 여러 가지 계면구조: $3.4{\pm}0.33{\times}10^{-12}$/ Torrl/sec)하여 LTCC 기판의 Hermetic sealing 특성에 관하여 조사하였다. 실제 적용의 한 예로 LTCC 기술을 이용하여 Bolometer를 성공적으로 진공패키징할 수 있었으며 실제 관찰된 이미지를 함께 소개한다.