• Korean Journal of Food Science and Technology
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• v.18 no.5
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• pp.351-356
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• 1986

The effects of drum spacing, steam pressure and drum speed on drying rate of minced fish flesh on both single and double drum dryers were studied. Starch additions in the form of tapioca flour up to 2.5% have been found satisfactory for aiding in sheet formation at the doctor blade. When the retention time was adjusted to maintain a constant product moisture, the highest production rate was obtained at the smallest drum spacing and the highest steam pressure within the limits of experimental conditions considered. The operating conditions suitable for producing the flakes with 5% moisture were: 100 kPa (steam pressure), 0.1 mm (drum spacing) and 3 rpm (drum speed). The production rate and overall heat transfer coefficient under these conditions were $12.1\;kg/m^2$hr and 950 $W\;/m^2K$ respectively. The drying data were fitted well to the conventional drying model, namely $MR\;=\;A\;\exp\;(-k{\theta})$, resulting in the various drying constants depending the operating conditions.

• Journal of Chest Surgery
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• v.38 no.4 s.249
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• pp.308-311
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• 2005

The status of pulmonary circulation is regarded with utmost importance for the successful Fontan operation. The absence of unilateral pulmonary artery leads to decreased pulmonary vascular bed and elevated pulmonary vascular resistance which are the risk factors for Fontan operation. A 9-year-8-month-old female patient diagnosed as tricuspid atresia, pulmonary atresia with absent left pulmonary artery flow, received extracardiac conduit Fontan operation using 18 mm Gore-Tex graft. She was discharged on twenty sixth postoperative day with arterial $O_2$ saturation of $70\%$ on room air. On last follow up at 14 months after the operation, she was clinically well with $O_2$ saturation of $91\%$.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.57-63
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• 2006

We have examined the electrical and optical characteristics of the plasma display panel(PDP) produced by vacuum in-line sealing technology. We found that the luminous efficiency was decreased as the base vacuum level was increased. For the base vacuum level of $1\times10^{-3}$ Torr, the firing voltage was 235V at the discharge gas pressure of 400 Torr and the luminous efficiency was 0.8 lm/W at 180V sustaining pulse. However, for the base vacuum level of $1\times10^{-6}$ Torr, the firing voltage was reduced to 215V and the luminous efficiency was improved to 2.5lm/w. Finally, we demonstrated successfully the operation of tip-less PDP fabricated using vacuum in-line sealing method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.567-572
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• 2013

In houses that use heating and cooling system, most of heat loss occurs through the windows, so that low-E glass, double-layered glass, and vacuum glazing are used to minimize the heat loss. In this paper, an encapsulating process that is a final process in manufacturing the vacuum glazing has been studied, and bonding in a vacuum chamber rather than atmospheric bonding was considered. For the efficiency of the encapsulating process, frit-melting temperature and bonding time were optimized with heater temperature, and the glass preheating temperature was optimized to prevent glass breakage due to thermal stress. Thus the vacuum glass was successfully manufactured based on these results and heat transmission coefficient measured was about $5.7W/m^2K$ which indicates that the internal pressure of the vacuum glazing is $10^{-2}$ torr.

• Journal of Biosystems Engineering
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• v.29 no.2
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• pp.131-140
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• 2004

본 연구에서는 배아미, 현미, 가능성쌀들 및 진공을 요하는 식품의 품질을 보존하기 위해서 연속식 자동진공포장기를 국내 최초로 개발하였다. 배아미의 진공포장 성공률은 92.6%이었고, 실패율 7.4%에서 진공포장기 자체에서 불완전 테이핑의 밀봉작업으로 진공이 서서히 풀리는 경우가 5.5%, 그리고 진공하기 전 자동비닐포장기에서 포장시 봉지 윗부분 밀봉이 불완전해 1.9%가 진공이 풀렸다. 이에 개발한 자동진공포장기의 진공포장성공률은 약 94.5%수준이었다. 진공포장기로 진공시간에 따른 진공압력을 측정하였고, 배아미 2, 3, 5 kg를 진공포장하는데 소요되는 시간은 각각 6, 8, 11초이었다. 진공포장으로 처리한 배아미와 진공포장 처리하지 않은 배아미를 각각 3재월간 저장실험하여 백도, 함수율, 과산화물가, 산가를 저장기간별로 분석하였다. 그 결과, 백도는 진공처리가 2 감소, 비처리가 4 감소하였고, 함수율은 진공처리가 0.8%감소, 비처리가 1.3%감소, 과산화물가는 진공처리가 최대 1.89 meq/kg까지 서서히 증가하였고, 비처리가 3.45 meq/kg까지 급속히 증가하였다가 서서히 감소하였다. 산가 역시 진공처리가 최대 0.71 mg/g까지 서서히 증가하였고, 비처리의 경우는 0.98 mg/g까지 급속히 증가하였다. 그리고 현미의 진공포장에서도 산가 및 과산화물가 변화가 배아미 경우와 비슷하였다. 또한 진공포장 제품에 인위적으로 쌀벌레들을 넣은 경우 15일 지나면 산소부족으로 모두 사멸하였다. 따라서 개발한 진공포장기로 진공포장한 경우 배아미 및 현미의 품질을 잘 보존할 수 있었다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.7
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• pp.529-536
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• 2020

Reaction Control System of the third stage of the Korean Space Launch Vehicle II conducts roll control and 3 axis control throughout third stage engine start, satellite separation, and collision and contamination avoidance maneuver. Reaction control system consumes its propellant in each thruster operation. Hence, loading of proper amount of the propellant is important for mission success. It is needed to have a rough estimation method of propellant consumption during the flight. In this paper, we developed a energy equation using pressure and temperature data which are acquired in the on-board reaction control system. We constructed a test system which is similar with the on-board reaction control system to verify the energy equation. Test results using deionized water were compared with estimated propellant consumption. We also conducted an error analysis of the energy equation. We also presented the propellant consumption result of a system level operation test.

• Tunnel and Underground Space
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• v.17 no.6
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• pp.464-474
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• 2007

An enhancement in the performance and safety of a high-level waste repository requires a validation of its engineered barrier. An engineering-scale test (named "KENTEX") has been conducted to investigate the thermal-hydro-mechanical behaviors in the engineered barrier of the Korean reference disposal system The validation test started on May 31, 2005 and is still under operation. The experimental data obtained allowed a preliminary and qualitative interpretation of the thermal-hydro-mechanical behaviors in the bentonite blocks. The temperature was higher as it became closer to the heater, while it became lower as it was farther away from the heater. The water content had a higher value in the part close to the hydration surface than that in the heater part. The relative humidity data suggested that a hydration of the bentonite blocks might occur by different drying-wetting processes, depending on their position. The total pressure was continuously increased by the evolution of the saturation front in the bentonite blocks and thereby the swelling pressure. Near the heater region, there was also a significant contribution of the thermal expansion of bentonite and the vapor pressure in the pores of the bentonite blocks.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2006.11a
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• pp.163-168
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• 2006

The combustion performance tests of a 30 tonf-class full-scale combustion chamber performed with kerosene as a coolant were described. The combustion chamber has chamber pressure of 53bara and propellant flow mass rate of 90kg/s. Since it was first firing test for 30tonf-class combustion chamber using kerosene cooling, kerosene coolant mass flow rate of 32kg/s which correspond to 120% of design mass flow rate were performed. Then, the firing test with kerosene mass flow rate of 25kg/s were successfully performed. The test results are described and the results showed that the kerosene cooling performance of this combustion chamber is sufficient and the firing test with regenerative cooling is feasible.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.69-73
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• 2009

Combustion test results of 1/2.5-scale thrust chamber for 75tonf-class liquid rocket engine were described. The thrust chamber has chamber pressure of 60 bar, propellant mass flow rate of 89 kg/s, and nozzle expansion ratio of 12. The combustion tests were conducted to verify the combustion performance, the regenerative cooling performance and the durability of thrust chamber at design point condition, and then were performed to confirm the operation and the combustion performance at low combustion pressure condition. All the tests had been successfully executed without the damage of the hardware. These test results present a possibility of hot firing test at low combustion pressure condition, and can be used as fundamental data to predict the combustion performance at design point condition for 75 tonf thrust chamber.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.110-110
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• 2017

마이크로 플루이딕 디바이스는 화학, 생물학 실험 및 생체 의학 진단을 위한 플랫폼으로 지난 20년간 그 사용 및 연구가 증가되어 왔다. 마이크로 플루이딕 디바이스를 제작하는 데 있어 가장 일반적으로 사용되는 재료는 실리콘이지만 비용이 많이 들고 불투명하므로 광학 검출이 필요한 곳에 적용이 제한된다. 이러한 측면에서 열가소성 플라스틱은 상업화의 중요한 요소인 대량 생산에 있어 큰 잠재력을 가지고 있으며 저렴하고, 가공이 쉽고, 유연하고, 광학적으로 투명하고, 화학적으로 불활성이며, 생체적합성을 가진다. 본 연구에서는 열가소성 플라스틱의 일종인 PMMA Poly(methylmethacrylate)를 효율적으로 접합하기 위해 비교적 낮은 온도와 낮은 압력에서 에탄올을 활용한 접착방식을 개발하였다. 먼저, PMMA 기판의 전체 표면을 $80^{\circ}C$에서 20 분 동안 에탄올로 처리한 후, $60^{\circ}C$에서 20 분간 열 압착하는 방식으로 영구적인 결합이 이루어졌다. 결합 강도 및 채널의 sealing 정도를 확인하기 위해, 인장 강도, 누수 및 파열 테스트를 수행하였다. 결합강도는 약 12.4 MPa로 타 연구와 비교할 때 매우 높았으며 마이크로 채널의 전체 내부 체적보다 거의 450 배 높은 강한 액체 흐름을 견딜 정도로 견고한 결합이 유지되었다. 열가소성 플라스틱의 본딩에 사용되는 유기 용매는 광학 특성을 희생시키지 않으면서 결합 속도를 높일 수 있지만, 결합 공정 중에 용매로 인해 마이크로 채널이 막히는 현상이 발생될 수 있다. 따라서, 견고한 본딩을 유지하면서 채널 막힘을 방지하기 위해 마이크로 채널을 소수성으로 선택적으로 처리하여 내벽의 표면 특성을 튜닝해 주는 기법을 추가로 적용하였다. 본 연구에서 사용한 방법은 아민-PDMS (polydimethylsiloxane) 링커를 적용하여 기판 표면의 극성을 변경시켜 주었다. 아민-PDMS 링커는 PC (polycarbonate), PET (polyethylene terephthalate), PVC (polyvinyl chloride) 및 PI (polyimide)와 같은 다양한 열가소성 플라스틱의 표면 소수성을 현저히 증가시키며 화학적, 열적 안정성이 뛰어나다. 아민-PDMS 링커는 PMMA의 카보닐 그룹과 반응할 수 있는 아민 사이드 그룹을 포함하는 PDMS 백본으로 구성되며 처리된 대상표면을 소수성으로 만든다. 아민-PDMS 링커 처리 이후 채널은 소수성으로 변화되었으며 이는 접촉각(contact angle)의 증가로 확인되었다. 코팅된 채널을 에탄올로 30분간 80도에서 처리하여도 소수성은 그대로 유지되어 마이크로 채널의 선택적인 소수성 코팅이 성공적으로 수행되었다.