• 융합신호처리학회논문지
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• 제23권4호
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• pp.228-233
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• 2022

본 연구는 수중 무인 이동체의 장기 운용을 위한 전기 에너지의 생성을 위하여 상변화물질(PCM)을 활용하는 방안에 대한 실험적 연구이다. 상변화물질이 온도에 따라 고체와 액체의 상태로 변하면서 발생하는 부피의 변화가 한정된 공간에서 고압으로 변환되어 이를 통해 유체의 흐름을 만들어 발전하는 방식이다. 상변화물질로 해양의 온도를 고려하여 폴리에틸렌글리콜(Polyethylene glycol)을 사용하였으며, 고체상태인 저온(1℃~2℃)과 액체 상태인 고온(21℃~25℃)에서 부피 변화를 압력으로 변환 시켜주는 전기 에너지 생성 장치를 제작하여 전기 에너지 생성 실험을 수행하였다. 실험 결과, 상(Phase)변화에 따른 압력 변화는 1시간에서 2시간 사이에 급격히 발생하였으며, 4시간 이후에는 약 24MPa 정도의 압력을 유지하였다. 이를 통해 상변화물질과 온도 차를 이용하여 수중 무인 이동체의 전원으로 활용할 수 있음을 확인하였고, 이를 적용하기 위해서는 좀 더 개선된 설계가 이루어져야 함을 알 수 있었다.

• Journal of Biosystems Engineering
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• 제40권1호
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• pp.61-66
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• 2015

Purpose: The purpose of this study was to establish conditions to dry a radish by examining the drying and quality characteristics depending on the air temperature and velocity of a far infrared conveyor dryer. Methods: A sample of weighing 6 kg was dried until the moisture content reached $15{\pm}0.5%$ (w.b.). Four temperatures (50, 60, 70, and $80^{\circ}C$) and three air velocity levels (0.4, 0.6, and 0.8 m/s) were employed as the drying factors. Results: The drying rate increased with the increase in the temperature and air velocity but decreased with time. However, the drying rate was influenced by temperature rather than velocity. At a temperature $50^{\circ}C$ with a air velocity of 0.4 m/s, it took 350 min for the radish to dry which was the longest drying time; $80^{\circ}C$ with a air velocity of 0.8m/s, it took 180 min for the radish to dry, which was the shortest drying time. ${\Delta}E$ (the color difference value) increased with the increase in temperature and air velocity. The browning and rehydration ratio increased as the temperature rose. Energy consumption decreased with the increased temperature and air velocity. Conclusions: Based on the results of this study, the best drying conditions for the radish were determined to be a temperature of $70^{\circ}C$ with an air velocity of 0.8 m/s.

• 한국도로학회논문집
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• 제17권5호
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• pp.1-10
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• 2015

PURPOSES : A finite difference model considering snow melting process on porous asphalt pavement was derived on the basis of heat transfer and mass transfer theories. The derived model can be applied to predict the region where black-ice develops, as well as to predict temperature profile of pavement systems where a de-icing system is installed. In addition, the model can be used to determined the minimum energy required to melt the ice formed on the pavement. METHODS : The snow on the porous asphalt pavement, whose porosity must be considered in thermal analysis, is divided into several layers such as dry snow layer, saturated snow layer, water+pavement surface, pavement surface, and sublayer. The mass balance and heat balance equations are derived to describe conductive, convective, radiative, and latent transfer of heat and mass in each layer. The finite differential method is used to implement the derived equations, boundary conditions, and the testing method to determine the thermal properties are suggested for each layer. RESULTS: The finite differential equations that describe the icing and deicing on pavements are derived, and we have presented them in our work. The framework to develop a temperature-forecasting model is successfully created. CONCLUSIONS : We conclude by successfully creating framework for the finite difference model based on the heat and mass transfer theories. To complete implementation, laboratory tests required to be performed.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.546-551
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• 2004

An applying Thermodynamic method for the purpose of measuring hydraulic efficiency of pump-motor system, based on IEC60041 code, is not easy to adopt at field test. Even though there were splendid development in measuring technic in discharge measuring through the hydraulic machina lots of unsolved problems concerned in flow-rate are still remain in measuring hydraulic efficiency in hydraulic machine. The key point in measuring hydraulic efficiency is to measure exact flow-rate. So, Thermodynamic methode provides a good solution. This methode measures hydraulic efficiency by detecting the difference of temperature and pressure between the hydraulic process of machine, without measuring flow-rate of pump or turbine. By measuring temperature in mk level and absolute pressure in pascal, we can get a difference of thermodynamic specific energy in Moliere chart before and after of hydraulic process, md that difference is equal to hydraulic loses. Following the standard in proceeding Thermodynamic methode, I hope these trial and records make others be familiar to the thermal methode and make it easer to beginner for trial.

• 한국주거학회논문집
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• 제13권2호
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• pp.73-78
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• 2002

Recently, the energy consumption has been sharply increased and the environmental pollution has been serious, resulted in increased use of fossil fuel. These facts are applied to most fields, and are especially important issues in the field of architecture. The energy consumption rate of building is about 30% of all energy consumption, and the rate of residential is about 20% of the rate of building and is increasing gradually. The purpose of this article is firstly to analyse an actual energy consumption rate of model building and compare it with alternative methods, which are applied passive system to, and secondly to suggest an optimal passive method for saving energy. The conclusion of this study is as follows; 1) As compared with the existing house on actual energy consumption rate, 6% in changing orientation to a south, 9% in using double low-e glazing and 23% in shading is decreased. 2) The change of insulation from 50 to 100mm did not show dramatical difference in energy consumption rate. 3) As changed indoor temperature at 2$0^{\circ}C$ in winter and 27$^{\circ}C$ in summer, the rate shows a reduction of 14% compared with the existing condition.

• 한국수소및신에너지학회논문집
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• 제33권2호
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• pp.176-182
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• 2022

Since the various characteristics of the polymer electrolyte membrane are not clearly identified, it is difficult to predict and design applications for various conditions. In this study, as a previous study on the aging of the polymer electrolyte membrane, a study was conducted on the change of mechanical properties according to the aging of the polymer electrolyte membrane. Through the tensile test of Nafion 117, the mechanical properties change due to aging was confirmed. As a result of the tensile test, it was confirmed that the aged Nafion 117 had reduced tensile strength. Through DSC measurement, aged Nafion confirmed that the glass transition temperature and enthalpy change were low, which is thought to be the effect of molecular motion and transition due to the lapse of time. The effect is thought to cause a difference in the amount of change in enthalpy, resulting in a difference in mechanical properties during tension.

• 농촌계획
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• 제9권4호
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• pp.35-41
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• 2003

The purpose of this study is on identifying the function of ground temperature arrangement of village grove. Case study was accomplished at Hacho village grove in Jinan-gun, Jeonbuk province. Hacho village grove was the largest grove of all and most formal grove in Jinan region. So ground temperature of outside and inside of Hacho village grove were measured from March to October in 2001. And comparative review about difference between outside and inside of village grove was accomplished. Our ancestors, in spite of orient and occident, have made a settlement in consideration of climatic conditions. We have to team from past pattern and add modern scientific technology. So traditional wisdom and wise planning process must be considered in order to create qualitative residential environment in present through natural elements. It is identified that in winter, the inner side ground temperature is higher than outside one of that and in summer, in contrary, the inner side one of that is lower than outside one of that. So it is identified that Macho village grove breaks winds and reduce the heating energy in winter, it reduces ground temperature and reduces cooling energy very well in summer. It is identified that village grove reduce ground temperature in summer better than any other season. It is identified that in summer, the effect of maintaining constant temperature is also better than my other season. So it is identified that village grove stabilize most changeable outside temperature in inside of that.

• 한국가금학회지
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• 제14권2호
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• pp.97-102
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• 1987

환경온도를 10, 20, 3$0^{\circ}C$로 처리할 때 산란계의 에너지 및 질소대사를 측정한 결과는 다음의 성적을 얻었다. 1) 산란계의 절식시열발생량(FHP)는 실온이 10, 20, 3$0^{\circ}C$로 상승함과 더불어 대사체중당 각각 89, 68, 52Kcal로 유의적으로 떨어지는 경향을 나타냈다. 2) 실온이 10, 20, 3$0^{\circ}C$로 상승함에 따라 사료섭취량은 109g, 101g, 79g 또 ME섭취량은 228, 203, 161Kcal로 점차 감소하는 경향을 보였다. 3) 실온이 10, 20, 3$0^{\circ}C$로 상승함에 따라 HP는 163, 130, 120Kcal로 감소하는 경향을 보이며 에너지축적(ER)은 64, 72, 41Kcal로 감소하였다. 4) 유지를 위한 ME요구량(MEm)은 실온 10, 20, 3$0^{\circ}C$에 있어 각각 128, 110, 110Kcal로 특히 저온일 때 MEm이 증가하고 있다. 또한 ME의 정미이용효율(NAME)은 각실온에서 64, 78, 69%를 보여 적온인 2$0^{\circ}C$에서 가장 높은 값을 나타내었다.

• Journal of Microbiology and Biotechnology
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• 제22권4호
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• pp.501-509
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• 2012

A 990 bp full-length gene (xynAHJ2) encoding a 329-residue polypeptide (XynAHJ2) with a calculated mass of 38.4 kDa was cloned from Bacillus sp. HJ2 harbored in a saline soil. XynAHJ2 showed no signal peptide, distinct amino acid stretches of glycoside hydrolase (GH) family 10 intracellular endoxylanases, and the highest amino acid sequence identity of 65.3% with the identified GH 10 intracellular mesophilic endoxylanase iM-KRICT PX1-Ps from Paenibacillus sp. HPL-001 (ACJ06666). The recombinant enzyme (rXynAHJ2) was expressed in Escherichia coli and displayed the typical characteristics of low-temperature-active enzyme (exhibiting optimum activity at $35^{\circ}C$, 62% at $20^{\circ}C$, and 38% at $10^{\circ}C$; thermolability at ${\geq}45^{\circ}C$). Compared with the reported GH 10 low-temperature-active endoxylanases, which are all extracellular, rXynAHJ2 showed low amino acid sequence identities (<45%), low homology (different phylogenetic cluster), and difference of structure (decreased amount of total accessible surface area and exposed nonpolar accessible surface area). Compared with the reported GH 10 intracellular endoxylanases, which are all mesophilic and thermophilic, rXynAHJ2 has decreased numbers of arginine residues and salt bridges, and showed resistance to $Ni^{2+}$, $Ca^{2+}$, or EDTA at 10 mM final concentration. The above mechanism of structural adaptation for low-temperature activity of intracellular endoxylanase rXynAHJ2 is different from that of GH 10 extracellular low-temperature-active endoxylanases. This is the first report of the molecular and biochemical characterizations of a novel intracellular low-temperature-active xylanase.

• 한국음향학회지
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• 제15권5호
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• pp.53-60
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• 1996

본 연구에서는 열음향 냉동기에 적합한 공명기를 열 및 음향학 이론에 근거하여 설계하는 방법론을 제시하고, 실제 제작하여 열음향 효과를 살펴보았다. 특히, 저온부의 열손실을 줄이고, 모세관 스택의 위치 및 길이를 최적화 함으로써 스택양단에서 온도차이를 크게 만드는 것을 목표로 하여 설계하고 제작하였다. 실험 결과, 33W의 입력전력으로 스택 양단에서 열부하가 걸려있지 않은 상태에서 22.7$^{\circ}$ 만큼의 온도차이를 얻어 내었고, 최저 4.3$^{\circ}$C까지 저온부의 온도를 낮추었다.