• Proceedings of the Korean Society of Postharvest Science and Technology of Agricultural Products Conference
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• 2003.10a
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• pp.214.1-214
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• 2003

본 연구는 4~6개월의 유아들을 위하여 재수화시킨 후 숟가락으로 떠먹일 수 있도록 쌀을 기본으로 하고 당근, 쇠고기 및 계란을 각각 주재료로 한 냉동건조 이유식 제조의 최적조건을 결정하기 위하여 수행되었다. 본 연구에서 얻어진 결과를 요약하면 다음과 같다. 당근, 쇠고기 및 계란이유식에서 모두 냉동건조시간은 수분함량이 높고 가열판 온도가 낮을수록 증가하였다. 파쇄성은 수분함량이 감소하고 가열판온도가 증가함에 따라 증가하였다. 관능적 특성 중 수화속도, 균질성 및 매끄러운 정도는 수분함량이 증가하고 가열판 온도가 감소할수록 증가였고, 뜨기 쉬운 정도는 수분함량이 증가할수록 증가하였으나, 가열판온도의 영향은 거의 받지 않았다. 또한 피막형성성은 수분함량과 가열판온도가 증가할수록 증가하였다. 이유식 제조치 최적조건은 당근이유식의 경우 수분함량 88.5%와 가열한 온도 34$^{\circ}C$로, 쇠고기이유식에서는 수된함량 88.5% 와 가열판온도 28$^{\circ}C$로, 그리고 계란이유식에서는 수분함량 87.5%와 가열판 온도 39$^{\circ}C$로 결정되었다.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.93-93
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• 2011

고진공 펌프 국산화의 일환으로 터보분자 펌프와 크라이오 펌프 개발이 진행 중이다. 크라이오 펌프 개발은 기계연구원, 우성진공(주), 국민대학교가 연합해서 수행하고 있다. 올해 9월말에 끝나는 1단계 마지막 3차 년도에는 두 고진공 펌프 모두 시제품을 완성하고 성능을 입증해야 한다. 이를 위해 고진공 펌프 개발과 별도로 진공 펌프 종합특성평가 시스템 개발도 표준과학연구원 주도로 진행되고 있는데 크라이오 펌프 평가 시스템은 원자력연구원이 담당하고 있다. 완성된 크라이오 펌프 성능평가 장치는 상온 기준 5${\times}$10-11 mbar의 기저압력을 보이고 있어서 초고진공 영역에서 크라이오 펌프 운전성능을 평가할 수 있는 준비를 마쳤다. 현재 크라이오 펌프 냉동기는 전반적으로 목표 설계치에 근접한 냉각성능을 나타내고 있는데 예를 들면 2차 냉각단 냉각능력이 10 K, 10 W로 대형 크라이오 펌프를 제작하기에도 충분하다. 활성탄 어레이도 여러 모델들을 자작하여 배기성능을 시험해 보았으므로, 최종적으로 3,600 L/s 급에 적합한 어레이를 만들고 이를 개발된 냉동기에 얹고 열차폐와 몸통을 씌워 펌프로서의 운전성능을 평가하는 일이 남아있다. 시제품은 상용품과 달리 기기가 차지하는 공간이 크고 부대설비가 복잡해서 운전성능 평가 장치에 부착해서 실험하기 어려울 수도 있으므로 기계연구원 현장에서 진공 게이지와 기체도입구만 부착한 마구리 플랜지를 펌프 흡기구 위에 달고 간이로 배기속도를 측정하는 것도 고려하고 있다. 이 경우는 표준용기를 사용할 때보다 배기속도가 과대평가되므로 이를 보정해 주는 방안을 마련해 놓아야 한다.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.447-452
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• 1988

In order to study effect of freezing rates on the quality changes such as pH, TBA value, free fatty acids and protein extractability, cylindrical chopped beef logs with 10cm of diameter and 10cm of height were frozen at three freezing rates(0.97cm/hr, 2.05cm/hr, 3.71cm/hr)using air blast freezer. Physicochemical changes of frozen meat were investigated during forzen storage at $-20^{\circ}C$ for 16weeks. Results on pH change showed $0.1{\sim}0.2unit$ increase at the 16th week of the frozen storage and the change was smaller with the increasing freezing rates. Free fatty acids content and TBA value also were increased during forzen storage, but they were minimal at 3.71cm/hr freezing rate. Correlation coefficient between TBA value and free fatty acids content were highly significant(r=0.804). After 16weeks of storage, extractibilities of salt soluble protein were decreased by 17.7%, 6.1% and 1.6% at freezing rates of 0.97, 2.05 and 3.71cm/hr, respectively. On the other hand, extractabilities of water soluble protein were decreased by 26.0%, 21.2% and 18.5%, respectively. The effect of freezing rates on the protein extractability appeared to be greater in salt soluble protein than in water soluble protein, but freezing denaturation was more rapid in water soluble protein.

• Parasites, Hosts and Diseases
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• v.30 no.2
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• pp.151-153
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• 1992

We have successfully cryopreserved free-living amoebae in order to maintain them feasibly under the conditions in our laboratory. The viability of trophozoites was higher when frozen by slow cooling (overall $0.7^{\circ}C$/min) than by fast cooling (overall $1.3^{\circ}C$/min). Glycerol and dimethylsulfoxide at the final concentration of 7.5% each was used for cryopreservation of free-living amoebae trophosoites. The survival rate was 2∼39% after storage in the liquid nitrogen for 60 days. Gross cultural or morphological changes were not noted in trophozoites thawed from frozen suspensions.

• Korean Journal of Food Science and Technology
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• v.28 no.4
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• pp.624-631
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• 1996

Effect of fluctuation range and intervals of defrosting temperature on quality of frozen foods stored in a domestic refrigerator equipped with an automatic defrost system was evaluated. As defrost system was operated, temperatures of domestic refrigerators were elevated from $-18^{\circ}C\;to\;-5^{\circ}C\;and\;-15^{\circ}C$, and fluctuation intervals were l6 hrs and 30 hrs, respectively. Quality deterioration such as protein denaturation, vitamin loss, exudate production and changes in appearance of frozen foods was minimized by reducing temperature oscillation during storage. Considerable effects of thermal oscillation on ice crystal sizes were observed for frozen beef tissue and ice cream. TTI (time temperature indicator) system also proved that the temperature control of defrost system in domestic refrigerator can improve the quality of foods during storage.

• Development and Reproduction
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• v.12 no.3
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• pp.221-229
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• 2008

For the clinical application, it is needed to keep characteristics of stem cells after storage for a long time. In the present study, we examined stem cell properties of human cord-derived stem cells (HUC) after cryopreservation. Cells were isolated from human umbilical cord and cultured in vitro. At passage 2 or 3, HUC were suspended at a concentration of $1.0{\times}10^6/m{\ell}$ in cryomedium consisting of DMSO and FBS. After freezing at $-80^{\circ}C$ overnight, HUC were cryopreserved at $-196^{\circ}C$ nitrogen gas. After 6 months, HUC were thawed and cultured in vitro. Assessment for the stem cell properties was made upon the morphology, population doubling time, and expression profiles of genes and various proteins. Cryopreserved HUC showed more than 70% viability and maintained fibroblast-like morphology similar to HUC before cryopreservation. Throughout the culture, they underwent average 42.8 doublings and produced $6.75{\times}{10^{18}}$ cells. RT-PCR analyses showed that cryopreserved HUC expressed Oct-4, nanog, SCF, NCAM, nestin, GATA-4, BMP4, and HLA-1 genes. They did not express Brachyury and HLA-DR genes. Immunocytochemical studies showed that cryopreserved HUC reacted with antibodies against SSEA-3, -4, Thy-1, vimentin, fibronectin, HCAM, ICAM, HLA-1 proteins. They did not react with antibody against HLA-DR protein. Theses genes and proteins expression patterns of cryopresserved HUC were similar to those of HUC before cryopreservation. These results suggest that cryopreserved HUC could retain proliferative potential and they expressed various genes and proteins similar to HUC before cryopreservation. Thus, cryopreservation might be useful for HUC for future research and clinical application.

• Journal of Chest Surgery
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• v.37 no.2
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• pp.113-118
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• 2004

The studies on cryopreserved arterial allograft have been focused on cooling methods, pre-treatment, cryoprotectant agents, and preservation temperature. But recently, several studies have reported that thawing methods also play an important role in the occurrence of macroscopic and microscopic cracks. This study was designed to investigate the cell injury after thawing, using a rabbit model to clarify the effect of thawing methods on cryopreserved arteries. Material and Method: Segments of the rabbit aorta were obtained and divided into 3 groups (n=60) according to whether the specimens were fresh (control, n=20), cryopreserved and rapidly thawed (RT) at 37$^{\circ}C$ (n=20), or cryopreserved and subjected to controlled, automated slow thawing (ST)(n=20). Cell damage was established using the TUNEL method and the morphological changes were also evaluated. Result: In the group that was rapidly thawed, the expression of TUNEL (＋) cells increased significantly more than in the slowly thawed group. In addition, the endothelial denudation, microvesicles and edema were significant in the rapidly thawed group compared with those changes in the slowly thawed group. Conclusion: Our study suggests that the rapid thawing method may be one of the major causes of cellular damage and delayed rupture in cryopresewed arterial allografts. The expression of TUNEL (＋) cells and structural changes were significantly low in the slowly thawed group, which might have contributed to the improvement of graft failure after transplantation.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.743-748
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• 2011

The performance of HFO-1234yf as a substitute for R-134a was evaluated in a household freezer/refrigerator. A series of tests such as 'refrigerant charging test, pull-down test, cooling speed test, and energy consumption test were carried out under the AHAM (Association of Home Appliance Manufacturers) standard. The results of a drop-in test were compared with those of a test conducted using R-134a. A test under a severe ambient air condition ($43^{\circ}C$) was also conducted. The result shows that the refrigeration cycle performance of HFO-1234yf is as good as that of R-134a ; however, the diameter of capillary tube should be increased in order to improve its performance in the cooling speed test.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.19 no.6
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• pp.92-99
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• 2005

We are interaction refrigeration warehouse cold water pump system and photovoltaic generation system. At this time, a target pressure is able to control in spite of change of the pressure according to pump head and rate of flow of pump. Also, we carry out the vector control of BLDC motor with the maximum torque operation and a high reliability from territory of each operation speed. Therefore, in this paper, we conclude energy saving technique of refrigeration warehouse cold water pump system.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.105-108
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• 2011

RFID(Radio Frequency Identification)를 이용한 창고관리시스템은 작업환경을 개선시키고 작업처리 속도와 정확성을 증가시킨다. RFID 기술은 기존의 바코드를 대체하여 물품관리를 네트워크화하고 지능화함으로써 창고의 물품관리에 혁신을 선도하고 있다. 그러나 RFID는 포장의 물질적 특성, 태그부착 위치, 노이즈 발생원이 있는 주위작업 환경 등에 따라 인식률에 상당한 차이를 낼 수 있고, 이러한 문제 때문에 실제 비즈니스 영역에서의 적용이 다소 제한받고 있다. 그러므로 RFID를 이용한 창고관리시스템이 모든 업무에 가동되어 업무 효율성을 높이기 위해서는 업무 흐름 도중에 발생할 수 있는 다양한 예외상황을 찾아내고 이를 빠르게 해결할 수 있는 방안이 필요하다. 본 논문에서는 RFID를 이용하는 냉동창고에서 업무 자동화가 끊어짐없이(seamless) 이어질 수 있도록 다양한 유형의 RFID 오류원인을 식별해내고 이를 해결할 수 있는 방안에 대해 제시한다. 이를 위해 RFID가 동작하는 작업환경을 업무 별로 분류하고, 각 작업환경에서 진행되는 업무흐름을 분석하여 각 오류를 유형별로 체계화 시킨다. 분류된 오류들에 대해 이를 감지하고 해결할 수 있는 방안을 찾음으로써 냉동창고 내의 전체적인 업무흐름을 원활히 하여 업무처리 소요시간을 줄일 수 있게 한다.