밀폐된 원통형 분무 연소기내의 자연발화 현상에 관한 수치적 연구

최지훈,백승욱,Choi, Ji Hun,Baek, Seung Wook 대한기계학회 1999 大韓機械學會論文集B Vol.23 No.6

In this study, the autoignition process of liquid fuel, injected into hot and stagnant air in a 2-D axisymmetric confined cylindrical combustor, has been investigated. Eulerian-Lagrangian scheme was adopted to analyze the two-phase flow and combustion. The unsteady conservation equations were used to solve the transition of the gas field. Interactions between two phases were accounted by using the particle source in cell (PSI-Cell) model, which was used for detailed consideration of the finite rates of transports between phases. And infinite conduction model was adopted for the vaporization of droplets. The results have shown that the process of the autoignition consists of heating up of droplets, vaporization, mixing and ignition. The ignition criteria could be determined by the temporal variations of temperature, reaction rate and species mass fraction. And the effects of various parameters on ignition phenomena are examined. These have shown that the increasing the reaction rate and/or the vaporization rate can reduce the ignition delay time.

Metal artifact 감소를 위한 CT simulator 영상 재구성의 유용성 평가

최지훈,박진홍,최병돈,원희수,장남준,구장현,홍주완,Choi, Ji Hun,Park, Jin Hong,Choi, Byung Don,Won, Hui Su,Chang, Nam Jun,Goo, Jang Hyun,Hong, Joo Wan 대한방사선치료학회 2014 대한방사선치료학회지 Vol.26 No.2

목 적 : CT simulation 시 고 밀도 인공물에 의해 발생된 metal artifact는 주변조직의 관찰능력 감소 및 CT number 변화에 영향을 미치게 된다. 본 연구에서는 CT 촬영 시 Metal Artifact Reduction for Orthopedic implants(O-MAR)의 유용성을 평가해 보고자 한다. 대상 및 방법 : CT simulator를 이용하여 Gammex phantom과 Rando phantom의 original 영상, 고 밀도 인공물을 삽입 후 획득한 non O-MAR 영상과 O-MAR 적용 영상을 획득하였다. CT 영상 평가를 위해 Gammex phantom CT 영상 내 5개 조직과 artifact 영향을 직접 받는 3개 지점에 관심영역(region of interest, ROI)을 각각 설정하고, CT number와 노이즈(standard deviation, SD)를 평균값으로 비교, 분석하였다. 고 밀도 인공물 주변조직의 CT number 변화에 따른 선량변화 확인을 위해 전산화치료계획시스템 Eclipse를 이용하여 Rando phantom CT 영상 3곳에 원기둥 체적을 형성하였다. 치료계획은 6 MV 광자선, 7개 조사면, 조사야 $15{\time}15cm$, 1회당 처방선량 100 cGy를 적용하여 수립하고 평균선량을 비교, 분석하였다. 두 실험 모두 original 영상을 기준으로 분석하였다. 결 과 : Gammex phantom을 이용한 영상평가 실험에서 각 영상별 5개 조직의 CT number 차이는 작았으며, artifact 영향을 직접 받는 3개 지점은 O-MAR 적용 시 original 영상과 유사하게 나타났다. 그리고 O-MAR 적용 시 8개 지점의 SD는 non O-MAR 영상보다 모두 감소되었다. Rando phantom을 이용한 선량변화 실험 또한 O-MAR 적용 시 original 영상과 유사하게 나타났다. 결 론 : O-MAR 적용 시 고 밀도 인공물 artifact로 인한 영상 왜곡 및 SD 감소로 영상의 질이 향상되었으며 CT number 보정에 유용하였다. 이는 체표윤곽도(contour) 생성 및 치료계획 수립에 이점이 있을 것이라 사료된다. Purpose : This study presents the usefulness assessment of metal artifact reduction for orthopedic implants(O-MAR) to decrease metal artifacts from materials with high density when acquired CT images. Materials and Methods : By CT simulator, original CT images were acquired from Gammex and Rando phantom and those phantoms inserted with high density materials were scanned for other CT images with metal artifacts and then O-MAR was applied to those images, respectively. To evaluate CT images using Gammex phantom, 5 regions of interest(ROIs) were placed at 5 organs and 3 ROIs were set up at points affected by artifacts. The averages of standard deviation(SD) and CT numbers were compared with a plan using original image. For assessment of variations in dose of tissue around materials with high density, the volume of a cylindrical shape was designed at 3 places in images acquired from Rando phantom by Eclipse. With 6 MV, 7-fields, $15{\time}15cm2$ and 100 cGy per fraction, treatment planning was created and the mean dose were compared with a plan using original image. Results : In the test with the Gammex phantom, CT numbers had a few difference at established points and especially 3 points affected by artifacts had most of the same figures. In the case of O-MAR image, the more reduction in SD appeared at all of 8 points than non O-MAR image. In the test using the Rando Phantom, the variations in dose of tissue around high density materials had a few difference between original CT image and CT image with O-MAR. Conclusion : The CT images using O-MAR were acquired clearly at the boundary of tissue around high density materials and applying O-MAR was useful for correcting CT numbers.

유럽 및 오세아니아의 기능성 축산물과 식육제품에 대한 운영현황 및 관리방안

최지훈,최윤상,김학연,김현욱,김진만,김천제,Choi, Ji-Hun,Choi, Yun-Sang,Kim, Hack-Youn,Kim, Hyun-Wook,Kim, Jin-Man,Kim, Cheon-Jei 한국축산식품학회 2010 한국축산식품학회지 Vol.30 No.5

본 연구는 유럽과 오세아니아의 선진국형 기능성 축산물 및 식육제품의 운영현황 및 관리방안을 연구 분석함으로서 국내 실정에 부합되는 규격기준 표준화와 관리방안 및 제도를 마련하는데 있어서 기초 자료를 제시하는데 있다. 우리나라를 비롯하여 전 세계적으로 국제경쟁력 강화 차원 등의 여러 여건 변화로 식품의 3차적 기능이 점차 강조되고 있다. 따라서 우리나라 자체적으로 기능성 축산물에 대한 정확한 정의와 범위를 확립하는 것이 시급하다. 식품에 기능성 표시를 허용하는 것은 이미 국제적인 대세이다. 유럽과 오세아니아에서도 별도의 기능성 축산물에 관한 법률이나 관리제도가 없으나 식품의 기능성 강화 측면에서 영양표시기준(nutrition claims)과 건강표시기준(health claims)을 통해 식품을 관리하고 있다. 강화 영양소에 대한 표시기준은 일부에 국한되어 있어 이들 기준을 사용하여 국내의 기능성 축산물 및 식육가공품에 적용할 경우, 기능성 지표물질 및 허용량의 설정이 반드시 이루어져야 할 것으로 보이며, EU와 호주 뉴질랜드에서 운영하는 제도 이외의 다른 선진국의 사례를 바탕으로 기능성 축산물에 대한 표준화가 이루어져야 할 것으로 보인다. 또한 기능성 축산물 및 식육제품의 표시를 확립하기 위해서는 현재 시중에 유통되고 있는 제품에 사용되는 기능성 소재 조사 및 각 기능성 소재가 인체에 유해한지 안전성에 대한 연구가 필요하며, 이들 소재의 적정 사용범위 설정을 위한 data base를 확립하기 위해 많은 실험적인 연구가 요구된다. It has recently been considered urgent to establish an accurate definition and scope of functional foods in the livestock industry in Korea. The tertiary function of food is gradually emphasized with various changes in conditions such as international competitive power enhancement of the whole world, including Korea. Therefore, the purpose of this study was carried out to gather basic information toward the establishment of standardization, management plans, and a system adapted to the Korean state through researching management systems of functional meat and meat products in the European Union (EU) and the Oceania Area (OA). A brief summary of this study is as follows. In the EU and OA, special management systems and laws about functional livestock and products were once nonexistent; only 'nutrition claims' and 'health claims' operated in the nutritional consolidation side of foods. Also, it was once thought that functional index materials and permissions established in the application of functional products sufficed, because management standards for enriched food were not established. Therefore, standardization of functional live stock products needs to be considered based on the case of developed countries in the EU and OA. It also seems that the above functional indicative substances can be applied, based on normal standards of indicative substances of functional products and the normal standards of indicators of functional substances added to livestock products presented in this study.

The Effects of Electric Grill and Microwave Oven Reheating Methods on the Quality Characteristics of Precooked Ground Pork Patties with Different NaCl and Phosphate Levels

최지훈,김학연,안광일,김천제,Choi, Ji-Hun,Jeong, Jong-Youn,Kim, Hack-Youn,An, Kwang-Il,Kim, Cheon-Jei Korean Society for Food Science of Animal Resource 2008 한국축산식품학회지 Vol.28 No.5

The objective of this study was to determine the effects of different reheating methods on the quality characteristics of precooked ground pork patties with different combinations of salt (1, 2%) and phosphate (0, 0.3%). The cooking and reheating methods used were the electric grill and the microwave oven. The cooking method and the addition of phosphate had detectable effects on the quality characteristics of ground pork patties. The reheating rate by microwave oven was faster than by electric grill, and decreased with increases in salt and the addition of phosphate. Cooking loss and reduction in patty diameter after reheating by microwave oven were higher than by electric grill, and these values decreased with increasing of salt/phosphate levels. The pH of patties with added phosphate was significantly higher than patties without phosphate, and no significant difference in pH was observed among patties reheated by each method. The patties reheated by electric grill had higher moisture contents than those reheated by electric grill, and the addition of phosphate resulted in higher moisture contents. The hardness of patties reheated by electric grill was lower than patties reheated by microwave oven, and the addition of phosphate increased the hardness with both reheating methods.

Marination 조건이 돈육 육포 제조용 양념육의 품질 및 최종 제품의 관능적 특성에 미치는 영향

최지훈,정종연,최윤상,한두정,김학연,이미애,이의수,백현동,김천제,Choi Ji-Hun,Jeong Jong-Youn,Choi Yun-Sang,Han Doo-Jeong,Kim Hack-Youn,Lee Mi-Ae,Lee Eui-Soo,Paik Hyun-Dong,Kim Cheon-Jei 한국축산식품학회 2006 한국축산식품학회지 Vol.26 No.2

본 연구는 marination 조건에 따른 돈육 육포 제조용 양념육의 품질 특성을 조사하고 최종 제품의 관능적 특성에 미치는 영향을 조사하기 위하여 실시하였다. 육포 제조용 양념액을 사용하여 침지 처리구는 1, 6, 12, 24, 48시간 동안 침지후 양념육의 품질 특성을 조사하였고 텀블링 처리구는 10, 20, 30, 60분 동안 텀블링한 후 조사하였다. 각 marination 조건별 육포의 평가를 위해 육포는 6, 12, 24, 48시간 침지시간이 경과된 양념육과 10, 20, 30, 60분 동안 텀블링을 실시한 양념육으로 제조하였으며, 관능 검사를 실시하였다. 침지 처리구와 텀블링 처리구 모두 염지 시간이 경과할수록 염지 수율과 보수력이 증가하였으며, 텀블링 처리구가 침지 처리구보다 높은 수율을 나타내었고, 보수력에서는 차이가 나타나지 않았다. 침지 처리구의 pH는 상승하는 경향을 보였으나 텀블링 처리구는 차이를 보이지 않았고, $L^*$-값과 $b^*$-값은 침지와 텀블링 처리구 모두에서 감소하였으나, $a^*$-값은 증가하는 경향을 보였다. 제조된 육포의 관능평가시 침지와 텀블링 처리구는 모두 뚜렷한 차이는 나타나지 않았으나, 모든 항목에서 30분 동안 텀블링을 실시한 후 제조된 육포가 좋은 평가를 받았다. 이상의 결과에서, 텀블링 방법으로 염지한 육포 양념육 및 육포의 품질이 침지 방법보다 우수하여, 텀블링 방법을 사용하여 우수한 품질의 육포를 제조할 수 있을 것으로 판단된다. The purpose of this study was to investigate the effect of marination condition(immersion and tumbling) on quality characteristics of cured pork meat and sensory properties of pork jerky. Pork meat was immersed for 1, 6, 12, 24, and 48 hours or tumbled for 10, 20, 30, and 60 minutes with curing solution. The jerky was made from cured pork meat immersed for 6, 12, 24, and 48 hours or tumbled fer 10, 20, 30, and 60 minutes. The curing yields and water holding capacity in immersion and tumbling treatments were increased as marination time increased, and the curing yields of tumbling treatments were higher than those of immersion treatments, but water holding capacity was not. The pH value of all treatments were not significantly different. CIE $L^*$- and $b^*$-value of immersion treatments were significantly decreased as marination time increased, but CIE $a^*$-value were increased. Objective color of tumbling treatments showed a similar tendency with those of immersion treatment. The sensory properties of pork jerky were not significantly different between immersion and tumbling treatments.

분쇄 계육 가슴살의 도체가공방법과 염지조건이 품질특성에 미치는 영향

최지훈,김일,정종연,이의수,최윤상,김천제,Choi, Ji-Hun,Kim, Il,Jeong, Jong-Youn,Lee, Eui-Soo,Choi, Yun-Sang,Kim, Cheon-Jei 한국축산식품학회 2009 한국축산식품학회지 Vol.29 No.3

This study was carried out to investigate the effect of hot boning and curing condition on the quality characteristics of ground chicken breast. Treatments were cured by four conditions follows; control (general curing method), T1 (after hot-boning and then immediately cured), T2 (after hot-boning and immediately cured, then frozen), and T3 (after hot-boning, immediately frozen, refrigerated and then cured). The pH of chicken breast in the state of pre-rigor was 6.22. The pH of cold storage or freezing chicken breast meat respectively were 5.70 or 5.61. The pH of T1 and T2 treatments were significantly higher than those of control and T3 treatment (p<0.05). After stored for 1 wk, the pH value of T1 treatment had a higher value than those of other treatments. T1 treatment had the highest water holding capacity and the lowest cooking loss among all treatments, regardless of the cooking methods. The reduction in diameter for T1 and T2 treatments was lower than those of control and T3 treatment (p<0.05). T1 treatment had the lowest fat loss and moisture loss among all treatments, and the emulsifying capacity of T1 treatment was the highest. The protein solubility of T1 treatment was significantly lower than that of T3 treatment.

파랑 주기에 따른 플로팅 구조물 모멘트 분석

최지훈(Choi, Ji Hun),채지용(Chai, Ji young),박정아(Park, Jeong Ah),이영욱(Lee, Young Wook) 한국콘크리트학회 2011 한국콘크리트학회 학술대회 논문집 Vol.2011 No.11

내부폭발하중을 받는 콘크리트 Tubular 구조물의 폭발저항성능 평가를 위한 실험방법 개발 및 구축

최지훈(Choi, Ji Hun),최승재(Choi, Seung Jai),양달훈(Yang, Dal Hun),김태균(Kim, Tae Kyun),김장호(Kim, Jang Ho Jay) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

내부폭발하중 시나리오에 따른 콘크리트 Tubular 구조물의 실험적 평가기법 개발

최지훈(Choi, Ji Hun),최승재(Choi, Seung Jai),이태희(Lee, Tae Hee),김장호(Kim, Jang Ho Jay) 한국콘크리트학회 2017 한국콘크리트학회 학술대회 논문집 Vol.29 No.2

폭발, 폭발 후 화재하중을 받는 이방향 프리스트레스트 콘크리트 패널부재의 실험적 거동 평가

최지훈(Choi, Ji Hun),최승재(Choi, Seung Jai),조철민(Cho, Chul Min),이치원(Lee, Chi Won),김장호(Kim, Jang Ho Jay) 대한토목학회 2016 대한토목학회 학술대회 Vol.2016 No.10