• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.105-110
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• 2010

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2011년도 제36회 춘계학술대회논문집
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• pp.200-203
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• 2011

Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.

• Journal of Advanced Marine Engineering and Technology
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• 제35권2호
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• pp.175-181
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• 2011

본 연구에서는 선박용 폐열회수 발전시스템에 적용 가능한 100kW급 구심터빈의 설계 및 CFD 해석기법을 이용하여 열사이클 시스템 및 구심터빈 최적화를 위한 설계자료를 확보하는 것이다. 구심터빈은 스크롤 케이싱, 18개의 베인노즐, 13개의 로터 블레이드로 구성되며, 해석격자는 격자테스트를 통해 약 230만개 정도의 최적격자를 구성하였다. 질량유량 0.5kg/s, 회전속도는 75,000rpm, 입구압력은 195~620kPa 범위 내에서 8가지 조건으로 설정하였다. 베인노즐 내부로 증기가 유입된 후 출구로 갈수록 노즐의 압력면과 흡입면의 압력이 비슷해지면서 마하수가 거의 같은 값을 보였다. 입구온도와 압력이 $250^{\circ}C$, 352kPa 일 때 등엔트로피 효율은 74%, 기계동력은 108kW의 해석결과를 보이고 있다.

• 한국식생활문화학회지
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• 제34권6호
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• pp.779-784
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• 2019

The purpose of this study was to optimize the rice protein extracted using a response surface methodology. The experiment was designed based on a CCD (Central Composite Design), and the independent variables were the high pressure (X₁, 0-400 MPa) and processing time (X₂, 0-10 minutes). The results of the extraction content (Y₁), residue content (Y₂), and recovery yield (Y₃) were fitted to a response surface methodology model (R²= 0.92, 0.92, and 0.93, respectively). Increasing the pressure and processing time has a positive effect on the extraction content (Y₁), residue content (Y₂), and recovery yield (Y₃). Therefore, these high-pressure conditions (independent variables) can significantly affect the improvement in rice protein extraction efficiency. Thus, the optimal conditions of X₁ and X₂ were 400 MPa and 10 min., respectively. Under these optimal conditions, the predicted values of Y₁, Y₂, and Y₃ were 62.93, 57.53 mg/g, and 91.76%, respectively.

• 한국축산식품학회지
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• 제33권4호
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• pp.474-480
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• 2013

This study was performed to investigate the effects of high pressure/high temperature (HPHT) treatment on the recovery efficiency and characteristics of porcine placenta hydrolysates. The placenta hydrolysates were characterized by solubility, free amino acid contents, gel electrophoresis, gel permeation chromatography (GPC) and amino acid composition. Placenta was treated at 37.5 MPa of pressure combined with various temperatures (150, 170, and $200^{\circ}C$) or various holding times (0, 30, and 60 min at $170^{\circ}C$). Insoluble raw placenta collagen was partially solubilized (> 60% solubility) by the HPHT treatment. Free amino group content of placenta collagen was increased from 0.1 mM/g collagen to > 0.3 mM/g collagen after HPHT treatment, reflecting partial hydrolysis of collagen. The molecular weight ($M_w$) distribution showed evidence of collagen hydrolysis by shifting of $M_w$ peaks toward low molecular weight when treated temperature or holding time was increased. Alanine (Ala), glycine (Gly), hydroxyproline (Hyp), and proline (Pro) contents increased after the HPHT treatments compared to a decrease in the others. In particular, the increase in Gly was obvious, followed by Hyp and Pro, reflecting that placenta hydrolysates were mainly composed of these amino acids. However, increasing temperature or holding time hardly affected the amino acid compositions. These results indicate that the HPHT treatment is advantageous to hydrolyze collagen derived from animal by-products.

• Korean Chemical Engineering Research
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• 제47권1호
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• pp.133-140
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• 2009

본 연구에서는 투과도 80 md, 하이드레이트 포화도 30%의 다중공 평판형 시스템에서 열자극 감압법에 의한 생산실험을 수행하여 하이드레이트의 해리양상 및 생산효율을 관측 및 분석하였다. 감압의 크기에 따른 실험결과에서, 운영 압력을 낮게 설정하면 높은 가스회수율을 얻을 수 있지만 생산초기 나타나는 강한 펄스가 생산전 운영에 무리를 줄 수 있다고 판단되었다. 또한 흡열반응에 의한 하이드레이트 재형성으로 오히려 회수율이 감소하는 경우가 발생하였다. 감압법 적용시의 생산거동을 더 상세히 분석하기 위해, 감압크기 140 psi와 320 psi에 대해 각각 4, 6회의 반복실험을 진행하였다. 그 결과, 140 psi로 감압크기를 설정한 경우, 생산초기에 불안정한 거동이 나타나지만, 빠르게 안정화됨을 알 수 있었다. 320 psi의 실험결과에서 불연속적이며 간헐적인 생산거동을 확인할 수 있었다. 열자극 실험은 안정적인 생산거동을 보이며 회수율이 비교적 낮아 열자극의 효과를 잘 관찰할 수 있는 압력차 80 psi를 적정운영 압력으로 설정하여 수행하였다. 열자극감압 혼용기법의 결과로부터 열자극시간이 증가할수록 가스회수율은 증가하였지만, 반면 에너지효율은 오히려 감소하는 것으로 나타났다. 열을 2분간 가한 후 열흡수 시간을 1분으로 설정한 경우 본 시스템에서는 회수율이 상승하였으며, 에너지효율 또한 증가되는 결과를 얻었다. 하지만, 열흡수 시간이 1분 이상일 경우 오히려 더 낮은 회수율과 에너지효율을 보였는데 이는 긴 열흡수 시간으로 인한 열손실에 기인한 것으로 판단된다.

• 한국막학회:학술대회논문집
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• 한국막학회 2004년도 첨단 분리막 연구동향
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• pp.37-59
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• 2004

Advantages : - Multi-functionality of inorganic surface ㆍMetal chelating ligand $\longrightarrow$ metal recovery .Alkylation $\longrightarrow$ hydrophobicity control - Enhanced stability ㆍThermal, mechanical and chemical stability ㆍSeparation in high temperature and pressure (omitted)

• 한국가스학회지
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• 제19권3호
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• pp.9-17
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• 2015

한국에서 소비되는 대부분의 천연가스는 배관을 통한 수송을 위하여 높은 압력으로 압축되고, 수요처에 공급되기 전에 정압기지에서 다시 감압된다. 감압과정에서 간단하고 효율적인 설치를 위해 팽창밸브가 사용되었으나 팽창밸브에서는 압축을 통해 회수되는 에너지가 없다. 따라서 팽창밸브와 동일한 감압 기능을 수행하면서 압력에너지를 축일로 회수하여 전력을 생산할 수 있는 터보팽창기가 팽창밸브의 대안으로 제시되었다. 본 연구에서는 중압 정압기지에서 팽창밸브의 평균 입구, 출구 압력조건인 68.7 bar에서 23 bar로 감압될 때 입구의 온도, 유량조건에 따라서 생산 가능한 전력을 이론적으로 계산하였다. Peng-Robinson 상태방정식을 이용하여 천연가스를 순수한 메탄으로 고려한 경우와 소량의 질소와 탄화수소의 혼합물로 고려한 경우에 대한 열역학적 물성을 계산하였다. 2013년 공급량을 기준으로 터보팽창기 도입을 통해 회수 가능한 이론적인 최대 전력생산량은 순수한 메탄의 경우 1596 MW, 혼합물의 경우 1567 MW로 추산되었다.

• 한국식품과학회지
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• 제25권1호
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• pp.28-32
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• 1993

들깨종자의 압착착유에 미치는 온도와 압력의 영향을 살펴보기 위해 생들깨와 볶은들깨의 기름의 추출율 및 압착케이크의 부피변형율을 각각의 온도, 압력 및 압착시간에서 관찰하였다. 본 실험을 위해 들깨종자의 수분함량은 2.5%로 조절하였고 온도는 30, 40, 50 및 $60^{\circ}C$가 사용되었고 압력은 10, 30, 50 및 70 MPa을 적용하였으며 압착시간은 5, 7, 9 및 11분을 적용하였다. 온도, 압력 그리고 압착시간이 증가할수록 기름의 추출율 및 압착케이크의 부피변형율은 증가를 하였다. 생들깨와 볶은들깨의 최대 추출율은 $60^{\circ}C$, 70 MPa, 11분에서 각각 85.59% 및 85.30%이었다. 추출된 기름의 점도는 지수함수적인 온도의존성을 보여주었으며, 점도가 낮을수록 즉, 온도가 높을수록 기름의 추출율은 증가하였다. 압착요인과 기름의 추출율 및 압착케이크의 부피변형율과의 상관관계 분석에서 압착요인의 효과는 압력, 온도, 온도${\times}$압력 그리고 압착시간 순으로 감소하였다. 온도(T), 압력(P) 그리고 압착시간(D)과 기름의 추출율(Y)과의 관계는 생들깨는 $Y=7.95+36.85P+1.12T^2-0.55TP-5.08P^2(r^2=0.97\;p<0.01)$였으며, 볶은들깨는 $Y=4.50T+39.23P+0.83T^2-1.71P-5.07P^2(r^2=0.99,\;p<0.01)$이었다.

• Journal of Chest Surgery
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• 제21권3호
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• pp.425-446
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• 1988

After 24 hours of preservation under 15 mmHg perfusion pressure the recovery rates of isolated canine hearts were determined. Preservation was performed in a cold room maintained at 4*C with 4 different types of perfusates bubbled with a mixture of 95% 0y and 5% CO~ using a modified perfusion unit designed in our institute. The perfusates used were as follows; Group 1: Krebs-Henseleit solution, Group 2: Krebs solution added by albumin and PGE1. Group 3: Modified Wicomb*s solution, Group 4: Modified Collin*s solution. The extent of myocardial recovery was evaluated using a modified isolated carmine perfusion model by measuring heart rate, systolic arterial pressure, left atrial pressure[LAP] and cardiac output. In addition to the above hemodynamic parameters, biochemical and enzymatic assays from perfusates and electron microscopic changes of the myocardium were also studied. The results were as follows; 1] The heart recovery rates were 41.6%, 53.4% and 108.9% in groups 1, 2 and 3, respectively, and group 3 elicited the best result[p< 0.001]. The heart beat was never recovered in group 4. 2] Recovered systolic arterial pressures[mmHg] were 63.3% in group 1, 94.9% in group 2 and 94.3% in group 3. 3] LAPs[mmHg] were 20 in group 1, 13.5 in group 2 and 11.2 in group 3, which suggested that the best myocardial preservation was elicited in group 3[p< 0.05]. 4] Cardiac output, the sum of aortic stroke volume and coronary leakage, were 69.1% in group 2, and 90.7% in group 3, but these were not statistically significant[p=0.24]. No aortic stroke output was measured in group 1 and 4. 5] The degree of myocardial edema increase was 17.5` in group 1, 24.6% in group 2, 20.9% in group 3 and 55.3% in group 4. But there were no statistical differences in each group[p= 0.08]. 6] CPK-MB[U/L] levels were increased 750% and 332%[p< 0.05], glucose levels[mg/dl] 60.5% and 78.2% and SGOT[U/L] levels 523% and 333%, in groups 2 and 3, respectively. Biochemical and enzymatic assays could not be performed in group 1 and group 4, because of poor recovery of heart beat. 7] Electron microscopic findings in the myocardium of most groups revealed slight to moderate muscle cell and mitochondrial edema. But all these findings were within the limits of reversible change. From these above results, it is suggested that modified Wicomb*s solution seems to be the most useful physiologic salt solution for preservation of the heart. We propose that after further study and improvement, our portable continuous hypothermic perfusion system will contribute to the development of a better preservation method for donor hearts for human heart transplantation.