• 한국산림과학회지
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• 제100권4호
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• pp.715-721
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• 2011

본 연구는 시험림에 양돈분뇨를 처리하여 수목의 지상부 biomass 및 질소저장 능력을 구명하는데 그 목적이 있으며 공시수종은 8개의 포플러(Dorskamp, 72-30, 72-31, Bonghwa1, Eco28, 62-10, Suwon, 97-18) 및 버드나무 클론(131-27) 그리고 기타 4수종(Liriodendron tulipifera L., Metasequoia glyptostroboides Hu and W.C.Cheng, Quercus palustris $M{\ddot{u}}nchh.$, Acer okamotoanum Nakai)이다. 지상부 biomass 구성 비율은 줄기, 가지, 잎의 순으로 높게 나타났으며, 지상부 biomass의 부위별 질소함량은 잎, 가지, 줄기의 순으로 높게 나타났다. 지상부 biomass 생산량은 양돈분뇨 처리구의 모든 수종 및 클론들이 평균 ha당 30 ton, 무처리구가 ha당 16 ton으로 나타나 양돈분뇨 처리구가 높았으며 양돈분뇨 처리구에서 Dorskamp 클론의 지상부 biomass 생산량이 ha당 48.3 ton으로 가장 높았다. 수목의 질소저장 능력은 양돈분뇨 처리구의 모든 수종 및 클론들이 평균 ha당 159 kg, 무처리구가 ha당 90 kg으로 나타나 양돈분뇨를 처리한 수종들의 질소함량이 높게 나타났으며 Dorskamp 클론이 ha당 286.5 kg의 질소를 저장해 가장 높게 나타났다. 따라서 Dorskamp 클론이 양돈분뇨 처리에 적합한 클론으로 나타났지만 양돈분뇨에 대한 내성 및 피해 등에 관한 연구가 지속적으로 필요할 것으로 판단된다.

• Journal of Advanced Marine Engineering and Technology
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• 제32권5호
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• pp.724-729
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• 2008

Umbilical cord blood has been recently considered an attractive potential alternative as a source of stem cell transplantation to curing diseases such as leukemia, cancers, immune disorders. Normally the stored system of the umbilical cord blood specimen is equipped with a computer-controlled robotic arm that enables the samples to locate the identification places in liquid nitrogen tank at regulated temperature as about $-196^{\circ}C$. As the half of robotic arm is in the air and the rest part is submerged in liquid nitrogen, the temperature of robotic arm varies from ambient to liquid nitrogen temperature. In this study the temperature variation of upper part of arm above tank lid was thermally analysed by using the commercial code of Ansys. The result of analysis was that the upper part of robotic arm was seriously frozen due to heat transfer from liquid nitrogen as low as -$120^{\circ}C$. In order to solve the frost problem of robotic arm, small PTFE tube block as resistance material was introduced into the lower part of tank lid instead of the whole stainless steel(SUS) robotic arm. The results showed that the temperature of robotic arm above the lid was higher enough, and this method would be one of the very effective measure to solve the problem.

• 한국초전도ㆍ저온공학회논문지
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• 제16권2호
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• pp.64-69
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• 2014

Measuring an exact amount of remaining cryogenic liquid propellant under microgravity condition is one of the important issues of rocket vehicle. A Pressure-Volume-Temperature (PVT) gauging method is attractive due to its minimal additional hardware and simple gauging process. In this paper, PVT gauging method using liquid nitrogen is investigated under microgravity condition with parabolic flight. A 9.2 litre metal cryogenic liquid storage tank containing approximately 30% of liquid nitrogen is pressurized by ambient temperature helium gas. During microgravity condition, the inside of the liquid tank becomes near-isothermal condition within 1 K difference indicated by 6 silicon diode sensors vertically distributed in the middle of the liquid tank. Helium injection with higher mass flow rate after 10 seconds of the waiting time results in successful measurements of helium partial pressure in the tank. Average liquid volume measurement error is within 11% of the whole liquid tank volume and standard deviation of errors is 11.9. As a result, the applicability of PVT gauging method to liquid propellant stored in space is proven with good measurement accuracy.

• 한국식품과학회지
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• 제32권6호
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• pp.1341-1349
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• 2000

젓갈 미생물 계수용 배지의 소금농도를 결정하기 위한 실험에서는 NaCl을 5% 첨가한 배지에서 가장 많은 수의 미생물이 계수되었고, 시료를 보존하기 위한 동결보호제는 glycerol 15%를 사용하였을 때 $-170^{\circ}C$에서 30일 보존 후 총균수는 75.5%, 젖산균수는 61.3%로 가장 높은 생존율을 나타내었다. 조개젓의 숙성과정 중 pH는 초기 6.8에서 5.0으로 낮아졌고, 숙성 후 단백질 함량은 조개젓은 10%, 멸치액젓은 $6{\sim}7%$이었다. 조개젓의 미생물수는 멸치액젓의 미생물수보다 많았고, 조개젓의 경우는 숙성기간에 따라 미생물수가 증가했다가 감소하는 경향을 보여주었으나 멸치액젓은 서서히 감소하는 경향을 보여주었다. 조개젓의 경우 숙성 4주까지 그램 양성, 카탈라아제 음성 세균들의 비율이 크게 증가하는 전형적인 젖산 발효 형태를 보여주었다. 젓갈을 $-170^{\circ}C$의 액체질소 탱크에서 2년간 보존 후 미생물수는 전체적으로 90% 이상 사멸하였고, 균총 변화를 보면 조개젓의 경우에는 그램 음성 세균과 간균의 생존율이 더 높았으나 거제 멸치액젓의 경우는 간균의 비율이 구균에 비해 감소하였다. 두 가지 젓갈에서 모두 효모의 비율은 크게 떨어졌다.

• E2M - 전기 전자와 첨단 소재
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• 제11권10호
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• pp.40-45
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• 1998

This paper describes a collaborative work between SEI and KEPCO on the Superconducting Magnetic Energy Storage system (SMES). We have studied two types of magnets. One is the 400kJ class LTS-SMES for testing the power stabilization operated at liquid helium temperature (4.2K) and the other is the 100J class HTS-SMES for confirming the possibility of applying HTS wire to SMES at liquid nitrogen temperature (77k). In this paper, the design of the magnet and the test results are described. Each magnet performed completely at rated operation.

• 한국수산과학회지
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• 제37권2호
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• pp.77-84
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• 2004

The powder and liquid products of seasoned and smoked skipjack tuna (Euthynus pelamis) was manufactured by using small skipjack tuna (1-2 kg, 20-30 cm) captured in the East Sea, Korea. Smoking was done three times at $80^{\circ}C$ for 8 hrs to decrease the moisture content below $15\%.$ The seasoned and smoked skipjack tuna powder with liquid smoke showed the lower pH than the control. The pH, VBN, amino nitrogen content, and TBA value were increased slowly as storage period was increased at room temperature. Liquid smoke decreased the production of animo nitrogen and VBN. Vacuum packaging was efficient for inhibiting the deterioration and the microbial growth of the seasoned and smoked skipjack tuna powder product.

• 한국환경농학회지
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• 제17권4호
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• pp.301-305
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• 1998

본 연구는 농가에서 사용하는 저류조, 연속 폭기조, 혐기성 정치식, 혐기성 교반식의 4가지 형태의 부숙조를 이용하여 액상 가축분 퇴비 부숙효율을 평가하기 위하여 수행하였다. 호기성 폭기조는 BOD 및 악취 제거율에서 혐기성 부숙방법보다 우수하였다. 반면에 질소는 초기농도의 47%가 손실되어 혐기성 부숙방법보다 심한 편이었다. 혐기성 부숙방법중 교반식과 정치식간에는 큰 차이는 인정되지 않았다. 그러나 혐기성 교반식이 정치식보다 대장균 제거율, 악취제거율은 더 높았으며, 질소 손실율은 더 낮게 나타났다. 농가에서 사용하는 저류조 형태의 부숙조는 혐기 또는 호기성 처리 방법보다 BOD, 대장균, 악취제거율등이 낮았다. 각 개별요인들의 효율을 종합 평가한 결과 액비 부숙효율은 혐기성 교반조>호기성 폭기조>무교반 혐기성조>저류조 순으로 높았다.

• 한국수소및신에너지학회논문집
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• 제27권6호
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• pp.642-650
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• 2016

One of the most feasible solution for reducing the excessive energy consumption and carbon dioxide emission is usage of more efficient fuel such as hydrogen. As is well known, there are three viable technologies for storing hydrogen fuel: compressed gas, metal hydride absorption, and cryogenic liquid. In these technologies, the storage for liquid hydrogen has better energy density by weight than other storage methods. However, the cryogenic liquid storage has a significant disadvantage of boiling losses. That is, high performance of thermal insulation systems must be studied for reducing the boiling losses. This paper presents an experimental study on the effective thermal conductivities of the composite layered insulation with aerogel blankets($Cryogel^{(R)}$ Z and $Pyrogel^{(R)}$ XT-E) and Multi-layer insulation(MLI). The aerogel blankets are known as high porous materials and the good insulators within a soft vacuum range($10^{-3}{\sim}1$ Torr). Also, MLI is known as the best insulator within a high vacuum range(<$10^{-6}{\sim}10^{-3}$ Torr). A vertical axial cryogenic experimental apparatus was designed to investigate the thermal performance of the composite layered insulators under cryogenic conditions as well as consist of a cold mass tank, a heat absorber, annular vacuum space, and an insulators space. The composite insulators were laminated in the insulator space that height was 50 mm. In this study, the effective thermal conductivities of the materials were evaluated by measuring boil-off rate of liquid nitrogen and liquid argon in the cold mass tank.

• Preventive Nutrition and Food Science
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• 제6권4호
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• pp.201-205
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• 2001

As a series of studies on improving the processing suitability of imported Pacific saury, oxidative stability of seasoned-dried Pacific saury treated with liquid smoke (T2 product) was examined during storage, comparing with control (C, seasoning only) and T1 (treatment of 0.05% BHT instead of liquid smoke). The pH of T2 treated with liquid smoke was relatively lower than those of C and T1 during storage. The contents of volatile basic nitrogen in all products increased continuously during storage. In the changes of TBA and POV of products during storage, the POV of T2 was lower than that of T1, and the TBA values of T1 and T2 were lower than that of C product. The major fatty acids were 22 : 1n-11, 20 : 1n-11, 16 : 0, 14 : 0, 22 : 6n-3, 20 : 5n-3, 18 : 4n-3, 16 : 1n-7, 14 : 1n-7 and 18 : 1n-9 in the both C and T2 products. The contents of polyunsaturated fatty acids in hath C and T2 somewhat decreased with increasing storage period, while those of saturated and monounsaturated fatty acids increased.

• 한국재료학회지
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• 제17권4호
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• pp.192-197
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• 2007

The effects of immersion time in the liquid nitrogen on the behavior of aluminum alloys used for the hydrogen storage tank of auto-mobile at cryogenic temperature were investigated. With increasing immersion time in the liquid nitrogen, the elongation of AI 5083 alloy at cryogenic temperature decreased because of non-uniform fracture of precipitates on the grain boundary, and the serration also occurred because of discontinuous slip due to rapid decreasing of the specific heat. The mechanical properties of AI 6061 alloy at cryogenic temperature were characterized by uniformed yield strength, tensile strength and elongation regardless of the immersion time in the liquid nitrogen. These mechanical properties of aluminum alloys at cryogenic temperature were interpreted by the strength of grain boundary and the slip deformation behavior.