In this study, FLUENT v.16.1 was used to investigate the compressible flow generated by the supersonic jet spewed from a high pressure tube. As the boundary condition for CFD (Computational Fluid Dynamics) analysis, the inlet temperature of air was constantly 300 K and the variation of JPR (Jet Pressure Ratio) were 5, 50, 100, 150 and the variation of tube diameter were 10, 20, 30 cm. As a result, it was confirmed that the effective range was increased as the JPR was higher, but it was confirmed that the effective range was lower than the JPR rise, and that the effective range was increased as the diameter was larger. Therefore, it is found that the tube diameter is more sensitive than the JPR among the influence factors of jet, and if the result of this study were reflected in the design of high pressure system, it will contribute to the design of the system for preventing the second accident.

This study was aimed to examine the potential of pre- and post-harvest treatment of chitosan and high pCO2 on the shelf-life of oriental melon fruit. Post-harvest dipping treatment of chitosan and high pCO2 did not bring any significant effect on the freshness of fruit in general, even at 1% of chitosan. Unlike post-harvest treatment, pre-harvest spray of chitosan significantly increased fruit firmness and firmness increase was higher in double sprays than single one. The internal quality such as soluble solid content and acidity was not altered by chitosan spray. No additional effect of high pCO2 with pre-harvest treatment of chitosan was found. Double sprays of chitosan showed significant effect on keeping visual appearance through delaying the incidence of skin browning. There was a potential of pre-harvest chitosan treatment on the shelf-life increase of oriental melon fruit and double sprays were better than single spray. However, high pCO2 seemed not to be effective on the storability of oriental melon fruit.

In order to investigate the low-cycle fatigue behavior of Inconel 718 alloy used for pressure vessels, the strain-controlled fatigue test was performed in the room and high temperatures of 550°C. High temperature test was done using an electric furnace attached on the hydraulic fatigue test system. Tensile strength and elastic modulus of the Inconel 718 alloy at the temperature of 550°C decreased by 8% and 10%, respectively, compared to those at the room temperature. Subjected to the repeated cyclic loading under the strain-control, the material exhibited cyclic softening behavior with decreasing yield strength at both room and high temperatures. The low-cycle fatigue properties determined in this research could be effectively used for the fatigue life estimation of high temperature components made of Inconel 718 alloy.

Medium pressure and mixed enzyme were used to hydrolyze raw anchovy under controlled conditions at a batchpilot plant-scale process for the production of anchovy protein hydrolysates (APH). Mass balance calculations were carried out so that the degree of protein solubilization and yields could be estimated. Almost complete hydrolysis could be achieved in 12 h, at 50oC and 75 MPa, with no pH adjustment, at 1% (10 g/kg) mixed enzyme using raw anchovy. This was achieved with the addition of water (1/2 raw anchovy/water). The degrees of protein solubilization and yield were 63.50% and 55.61%, respectively. Fractionation using UF/NF pilot scale systems was carried out for producing four different fractions on the APH. Successive fractionation on UF and NF membranes allowed the concentration of the peptides of selected sizes without, however, carrying out sharp separations, and with some MW classes being found in several fractions. Spray drying processes for 10 kDa permeate were described to increase their usability. The free amino acid profile of the fractions was identical to that of the APH.

In this study, ultra-fine soft-magnetic micro-powders are prepared by high-pressure gas atomization of an Fe-based alloy, Fe-Hf-B-Nb-P-C. Spherical powders are successfully obtained by disintegration of the alloy melts under high-pressure He or N2 gas. The mean particle diameter of the obtained powders is 25.7 μm and 42.1 μm for He and N2 gas, respectively. Their crystallographic structure is confirmed to be amorphous throughout the interior when the particle diameter is less than 45 μm. The prepared powders show excellent soft magnetic properties with a saturation magnetization of 164.5 emu/g and a coercivity of 9.0 Oe. Finally, a toroidal core is fabricated for measuring the magnetic permeability, and a μr of up to 78.5 is obtained. It is strongly believed that soft magnetic powders prepared by gas atomization will be beneficial in the fabrication of high-performance devices, including inductors and motors.

This study investigates the thermal shock property of a polycrystalline diamond compact (PDC) produced by a high-pressure, high-temperature (HPHT) sintering process. Three kinds of PDCs are manufactured by the HPHT sintering process using different particle sizes of the initial diamond powders: 8-16 μm (D50 = 4.3 μm), 10-20 μm (D50 = 6.92 μm), and 12-22 μm (D50 = 8.94 μm). The microstructure observation results for the manufactured PDCs reveal that elemental Co and W are present along the interface of the diamond particles. The fractions of Co and WC in the PDC increase as the initial particle size decreases. The manufactured PDCs are subjected to thermal shock tests at two temperatures of 780oC and 830oC. The results reveal that the PDC with a smaller particle size of diamond easily produces microscale thermal cracks. This is mainly because of the abundant presence of Co and WC phases along the diamond interface and the easy formation of Co-based (CoO, Co3O4) and W-based (WO2) oxides in the PDC using smaller diamond particles. The microstructural factors for controlling the thermal shock property of PDC material are also discussed.

The hydrogen embrittlement of two austenitic high-manganese steels was investigated using tensile testing under high-pressure gaseous hydrogen. The test results were compared with those of different kinds of austenitic alloys containing Ni, Mn, and N in terms of stress and ductility. It was found that the ultimate tensile stress and ductility were more remarkably decreased under high-pressure gaseous hydrogen than under high-pressure gaseous argon, unlike the yield stress. In the specimens tested under high-pressure gaseous hydrogen, transgranular fractures were usually observed together with intergranular cracking near the fracture surface, whereas in those samples tested under high-pressure gaseous argon, ductile fractures mostly occurred. The austenitic high-manganese steels showed a relatively lower resistance to hydrogen embrittlement than did those with larger amounts of Ni because the formation of deformation twins or microbands in austenitic highmanganese steels probably promoted planar slip, which is associated with localized deformation due to gaseous hydrogen.

본 연구에서는 최대한 인삼의 외형을 원형삼 형태의 홍삼 과 유사하게 유지하면서도 기능성은 증진시킬 수 있는 신속 한 고온고압 처리 공정을 확립하기 위하여 다양한 고온고압 처리공정 조건에 따른 이화학적 성분 특성 및 항산화 활성 변화를 살펴보았다. 산성다당체 및 홍삼 특유의 진세노사이 드 Rh1, Rg2, Rg3의 함량은 140℃, 3 kg/cm2의 고온고압 처리 조건에서 가장 높은 반면, 총 페놀 화합물 및 말톨 함량은 156℃, 5 kg/cm2의 고온고압 처리조건에서 가장 높았다. 그러 나 홍삼의 증자 처리 시 156℃, 5 kg/cm2의 처리조건에서는 시 료가 터지거나 외형의 변형이 심하기 때문에 140℃, 3 kg/cm2를 최적 온도 및 압력으로 설정하였다. 한편, 증자 시간이 증 가함에 따라 총 페놀 화합물, 말톨 및 흑삼특이 진세노사이드 함량은 지속적으로 증가하는 경향을 나타내었으나, 20분간 처리한 군의 외형이 기존의 홍삼과 가장 유사한 외관을 나타 냈으므로, 140℃, 3 kg/cm2에서 20분 동안 증자 처리하는 것 을 본 실험의 최적 조건으로 설정하였다. 최종적으로 이러한 최적조건을 통해 제조된 홍삼의 항산화 효능을 분석한 결과, 시중에서 판매되는 백삼, 홍삼 및 흑삼과 비교하여 높은 항산 화 성분 및 항산화 활성을 나타냈다. 따라서 본 연구를 통해 확립된 고온고압 처리를 통한 신규홍삼 제조기술은 그 형태 가 기존의 홍삼 제품과 유사하면서도 공정이 신속하고, 품질 은 흑삼과 비슷한 고기능성 신규 인삼제품 개발 시 응용 가능 한 공정으로 사료된다.

The measuring equipment capable of thermo measuring of wide range thermo range(0℃ ~ 160 0℃) will be developed in a high temperature and high pressure state. The developed technology is a combination of one measuring two different temperatures measured in the measuring to a high temperature as possible at a low temperature from thermocouple module(thermocouple) to develop an integrated measuring device capable of measuring the broadband. Also, to develop two or more guard module to ensure the water-tightness and durability of the device to develop in a vacuum or high pressure is applied to the one-piece measuring device.

The purpose of this research was to investigate the effect of weighting agent (WA) and high pressure homogenization (HPH) on the stability of water-in-oil-in-water double emulsion (DE). To prepare oil phase (O), olive oil, glycerol ester of wood rosin (WA; variable 1), and polyglycerol polyricinoleate (lipophilic emulsifier), and for interior water phase (W1), deionized water, gelatin, sodium chloride, ascorbic acid, and green tea extract(core material) were mixed and heated. When temperature of O and W1 reached up to 60℃, W1 was dispersed into O dropwisely followed by magnetic stirring at 1500 rpm for 2 min (O:W1=3:1). By applying homogenization at 4000 rpm for 2 min followed by ultrasonication for 4 min, water-in-oil primary emulsion (PE) was produced. And resting PE at 4℃ for 30 min was followed. For exterior water phase (W2), deionized water, sodium chloride, ascorbic acid, and polysorbate 80 (hydrophilic emulsifier) were mixed. When temperature of PE reached at room temperature (24 ± 2℃), PE was dispersed into W2 dropwisely followed by magnetic stirring at 1500 rpm for 15 min (PE:W2=1:3). By applying ultrasonication for 2 min followed by HPH at 500 bar for 1 to 3 times (variable 2), DE was produced. When DE was freshly produced, phase separation occurred at different period of time depending on whether variable 1 and 2 were applied or not (from 5 min to more than a day). The structure of DE was observed through optical and transmission electron microscopy. And relationship between the mean size of oil droplets and the occurring time of phase separation was studied. DE can be used as an appropriate delivery system for co-loading both hydrophilic and lipophilic bioactive compounds simultaneously, and promoting industrialization as well by applying it to food products, for example, beverage.

This study was carried out to improve the performance of sewer trenchless entire repair method by using the multifunctional safety high-pressure hose. Because the flexural strength and flexing modulus of elasticity increased in the range from 60℃ to 80℃ of the setting temperature, the unform quality was secured to satisfy the standard quality and consolidate the strength, by supplying steam to the entire sewer through the safety high-pressure hose simultaneously. After the steam was supplied, the temperature of the condensate water with a large amount occurred , compared with a small amount, was very low. So, the setting time was shorter over than one hour by reducing the unsatisfied cure state and excluding the condensate water. The standard quality increased by approximately 15% at upper, central, and lower points of the same sewer was gained from the test result of CIPP(cured in place pipes) constructed at the optimum setting temperature. The steam and air were supplied evenly to the sewer by controlling the safety high-pressure hose in the tense and relaxed state and by using the exclusive function of condensate water. The availability and safety for the constructed process were achieved.

This study was performed to investigate the enrichment of pterostilbene content and improvement of biological activity in harvested blueberries through the modulation of metabolism with high pressure treatment at hormetic doses. After harvested blueberries were pressurized under 2, 10, and 20 MPa for 5 min at 25oC along with a set of control, pterostilbene content and induction of quinone reductase activity were observed. As a result, the content of pterostilbene in high pressure treated blueberries was enriched up to 1.33 times while quinone reductase activity was improved compared to the untreated sample. These results suggest that a mild high pressure treatment can enrich pterostilbene content and improve biological activity in harvested blueberries according to hormetic response.

Effects of dynamic high-pressure (DHP) treatments with and without integration with heating on microbial stability, vitamin C concentration, color, sugar content, and pH of orange juice were studied and compared with those of the conventional thermal treatment. Freshly squeezed orange juice was heated at 90oC for 1 min or DHP-treated at 205 MPa and 20, 50, 60, or 70oC. The DHP treatment at 20oC without heating and the treatment at 50oC inactivated indigenous mesophilic aerobic microorganisms in orange juice by 4.2 and >7 log CFU/mL, respectively. The DHPtreated juice exhibited brighter color and higher vitamin C concentration and sugar content than the thermally treated juice, regardless of integration with heating. The DHP-treated juice demonstrated brighter color and higher sugar contents than untreated juice and thermally treated juice during storage at 4oC for 63 days. The results have demonstrated the potential of applying DHP treatments to pasteurize orange juice with increasing brightness and sugar content of the juice.

본 연구에서는 영·유아용 주스의 유동 특성과 과채류의 색소 성분이 지니고 있는 생리활성이 강화된 혼합과채주스 의 생산가능성을 조사하기 위하여, 생과일과 채소를 혼합 하여 착즙한 적색, 황색 및 녹색의 혼합과채주스를 조제한 후 영양균형과 유통 특성을 부여하기 위하여 물리적으로 변성된 현미 가루를 4% (w/w) 첨가한 후에 품질변화를 최소화하고 유통 중 저장 안전성과 점증 효과를 좀 더 부 여하기 위하여 초고압 처리(20oC, 500 MPa for 3 min)를 한 후 4oC에서 4주간 저장하면서 품질 및 총균수의 변화 를 측정하였다. 착즙된 FV juice에 물리적으로 변성된 현미 분말을 첨가 함으로서 기대하였던 바와 같이 시중에 유통되고 있는 영 ·유아용 과일주스에 비하여 단백질 및 지방이 약 10배 정도 증가되고 섬유질이 검출되어 영양학적으로 강화되고, 색도가 선명하여 소비자의 기호도를 충족시킬 수 있으며 항산화 활성이 검출되어 생리활성 또한 강화된 제품을 제 조할 수 있었다. 뿐만 아니라 영·유아용 주스의 유동 특 성에 적합한 물성인 spoonful 특성과 아주 작은 점성 증가 에 의해서 야기되는 spreadability의 감소를 물리적으로 변 성된 현미 분말 첨가와 초고압 처리(500MPa for 3 min)에 의해서 확보할 수 있었다. 4oC에서 4주간 저장 중에 품질 변화(pH, 당도, 색도, 및 항산화 활성)와 총균수를 측정한 결과, pH와 당도는 초고압 처리에 관계없이 저장 중에 변 화가 매우 미미하였고 색도, 항산화 활성은 저장 시간에 따라 제조된 주스 별로 약간의 차이는 있지만 감소하는 경 향을 나타내었다. 총균수의 경우에는 저장 기간 내내 과채 류 주스의 국내 기준·규격인 1.00×105 CFU/mL 보다 적 게 유지되었다. 다만 HPP-GB juice의 경우에는 104 CFU/ mL로 제어되어 초고압 처리 이전 공정에서 102내지 103 CFU/mL로 제어되어야 하는 위생관리의 중요성이 확인되 어, Bacillus spp.의 제어를 분명하게 실시하여야 한다. 종 합하여 판단하면, 영·유아용 과채혼합주스의 유동 특성과 과채류의 색소 성분이 지니고 있는 생리활성이 강화된 초 고압 처리 과채혼합주스의 생산 및 냉장 유통 가능성을 확 인할 수 있었다.

This study involved the shape of water jet nozzle to promote blasting ability and an increase of projection distance when cleaning VLBC cargo hold. Simulation of water jet projection process inside VLBC cargo hold was done in both 2D and 3D environment. The result are promising since both case show the capability of water contacting the desired target.

초고압 처리에 의한 메밀 반죽의 변화를 반죽의 미세 구조, 열 특성 평가, 조직감 측정을 통하여 확인하였다. 초고압 처리 강도와 시간에 따라 메밀 반죽 내 미세 구조를 관찰 시, 압력의 강도와 처리 시간이 증가함에 따라 전분의 호화가 일어나며 조밀한 구조를 가지게 되었다. 이러한 현상은 메밀 반죽의 조직감에 영향을 미쳐 압력이 증가함에 따라 탄성, 부착성, 씹힘성을 감소시키고 압력 처리 시간을 달리하였을 때 장시간 압력 처리에 따라 탄성, 씹힘성, 검성이 더 높은 값을 가짐을 확인하였다. 면의 끊어짐에 관련된 특성인 인장도는 소비자가 면을 섭취할 때 관능적 품질의 중요한 요소로서, 초고압 처리 시 글루텐을 함유하지 않는 메밀 반죽의 인장성을 나타내는 failure tensile distance를 증가시키는 결과를 얻었다. 따라서 메밀을 비롯한 다른 곡물을 활용한 gluten-free면 제품의 제조 시 초고압공정을 활용할 경우 기존 제품의 단점을 개선할 수 있을 것으로 예상된다.

본 실험은 초고압과 입자도 차이에 따른 더덕의 외피와 육질의 항산화 활성을 비교 진행하였다. 외피의 경우 입자도 크기에 따른 항산화 활성의 유의 차가 나타나지 않았지만, 육질의 경우에는 입자도 크기에 따른 항산화 활성의 유의 차가 나타났다. 초고압 하에서 실시한 더덕 외피에서는 입자도간 항산화 활성의 유의차가 나타나지 않았다. 반면 육질에서는 초고압 처리한 압력에 따라 또한 측정한 항산화 성분에 따라 입자도 간에 유의차가 나타났다. 이와 같은 현상은 시료를 구성하는 물질이 서로 다른 경도를 지니고 있어서 내부저항에 차이가 생기는 것에 기인하며 초고압 처리가 내부저항에 작용하는 정도에 따라 기인되었을 것으로 추론한다. 이 같은 결과로 더덕을 외피와 육질을 분리하지 않은 채 입자도 영향을 분석할 경우 입자의 크기가 큰 영역에 항산화도가 높은 외피가 많이 분포되어 오히려 항산화도가 높음을 관찰하였다.

주스의 품질악화를 초래하는 효소를 불활성화시키기 위해서 감귤 주스와 사과 주스 추출물에 초고압 처리와 열처리를 하여 각 시료의 PPO와 POD의 불활성화 정도를 확인하고 동역학 모델에 적용하여 이들의 불활성화 특성을 연구하였다. 감귤 주스와 사과 주스에서 모두 PPO가 POD보다 열과 압력에 대해서 상대적으로 내성을 갖는 것을 알 수 있었으며, 초고압 처리 과정을 거쳤을 때 보다는 열처리 과정을 거쳤을 때 PPO와 POD가 효과적으로 불활성화되는 것을 확인할 수 있었다. 초고압 기술은 처리 후에도 제품의 영양분과 색의 변화에 영향을 미치지 않기에, 최상의 상태와 품질로 제품을 제공 할 수 있는 장점을 가지고 있지만, 효소를 불활성시키기에는 부족하다는 단점을 가지고 있다. 이를 보완하여 산업적으로 이용되어지기 위해서는 영양분이 파괴되지 않는 열 처리 조건을 잡고, 효소를 효과적으로 불활성시킬 수 있는 초고압 처리 조건과 결합하여 최상의 결과를 얻을 수 있는 조건을 찾는 연구가 필요하다고 판단된다.

This study involved the shape of water jet nozzle to promote blasting ability and an increase of projection distance when cleaning VLBC cargo hold. Furthermore, I researched the effect of pressure, length of reducer, nozzle caliber size and nozzle shape on the nozzle through CFD simulation. Simulation of water jet projection process inside VLBC cargo hold was done in both 2D and 3D environment. Simulation results show installing suitable nozzle can increase the cleaning effect of cargo hold.