In this study, gas flow pattern and temperature distribution in a laboratory scale low temperature furnace for carbonization were numerically analyzed. The furnace was designed for testing carbonization process of carbon fibers made from polyimide(PI) precursor. Nitrogen gas was used as a working gas and it was treated as an ideal gas. Three-dimensional computational fluid dynamics analysis for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The results showed that more uniform velocity profile and axisymmetric temperature distribution could be obtained by varying mass flow rate at the inlets.

Because of the International Maritime Organization(IMO)'s regulation to regulate emissions of ships, a change is taking place to replace ship fuels from Heavy Fule Oil(HFO) to Liquefied Natural Gas(LNG). In the case of LNG, it is a material obtained by liquefying Natural Gas(NG), and it is -163 degrees below zero, and the volume is reduced to 1/600 level. The material of the tank that can store LNG must be a material that can safely store LNG in a cryogenic environment, and the materials of the tank that can store LNG are limited in the International Code of the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk(IGC Code). Among the materials listed in the IGC Code, 9% nickel steel is used as a material for LNG fuel propulsion tanks that are recently ordered because of relatively high mechanical properties under cryogenic environments. In this study, butt welding was performed on a 9% nickel steel material using Flux Cored Arc Welding(FCAW), the most widely used welding method in shipyards. In PARTI, after securing the welding conditions, cross-sectional observation results analysis, liquid penetrating test, and radiographic test were performed to verify the reliability of the weld.

연중생산이 가능하고 특히, 저온에서 화색발현이 우수하며 볼륨감 있는 스프레이국화 신품종을 개발하기 위하여 충청남 도농업기술원 화훼연구소에서 2010년에 모본으로 황색의 홑꽃 ‘SP09-251-01’를 부본으로 ‘SP08-010-16’계통을 인공수분 하였다. 종자 파종은 2011년에 실시하였고, 실생개체 중 화색과 화형이 우수한 281번째 개체를 선발하여 ‘SP11-103-05’로 계통명을 부여하였다. 주년생산성 검정을 위하여 2011년부터 2013년까지 자연일장, 전조재배, 차광재배를 각각 실시하였고, ‘Yes Holic’과 화형, 화색, 초형이 비슷한 ‘Jazz’ 품종을 대조품 종으로 사용하였다. ‘Yes Holic’ 품종은 2013년에 국립종자원에 품종보호 출원을 하였다. ‘Yes Holic’은 황색(Yellow 7A)의 꽃잎과 녹색(Green 1B)의 화심색으로 조사되었고 자연일장 작형의 개화기는 10월 25일로 ‘Jazz’의 10월 26일에 비해 빨랐다. ‘Yes Holic’의 초장과 줄기굵기는 각각 80.2cm와 6.1mm 로 ‘Jazz’의 78.6cm와 5.3mm보다 컸다. ‘Yes Holic’의 꽃 직경은 4.4cm로 ‘Jazz’의 4.1cm보다 컸으며, 착화수도 ‘Yes Holic’ 가 29.4개로 ‘Jazz’의 22.1개보다 많았다. 흰녹병저항성은 ‘Yes Holic’이 10%이하의 발병율인 3단계로 흰녹병이 저항성이 높은 것으로 확인되었다. 재배상 유의사항은 ‘Yes Holic’은 소등 후 야간온도를 18℃로 가온하면 고유화색 발현과 적당한 착화수 확보 및 균일한 개화가 가능하다. 그리고 여름철 고온기에는 ‘Yea Holic’의 총포에 잿빛곰팡이병이 주로 발생되므로 스크린과 포그를 활용하여 주간온도를 낮추고 봉오리 착색기에 전용 농약을 살포해 주어야 한다.

본 연구는 정수압 처리와 초음파 처리가 20일 숙성기간 동안 돈육의 삼겹살과 목살 부위의 품질특성에 미치는 영향에 대해 조사하였다. 다양한 품질특성을 관찰한 결과 정수압에서 숙성하고 초음파 처리한 돈육은 부위별로 효과의 차이는 있지만, 품질향상에 효과적인 것으로 나타났으며 또한, 초음파 처리했을 때 특히 고기의 연도와 관계가 있는 pH, 보수력, 경도 품질을 높이는 것으로 관찰되었다. 본 연구에서 이용한 저온 정수압 숙성 및 초음파 처리공정은 낮은 온도에서 돈육을 빠른 시간안에 숙성하는데 적용 가능할 것으로 판단된다.

본 연구에서는 국내에서 소비도 및 인지도가 높은 식용 버섯인 큰느타리(Pleurotus eryngii), 느타리(Pleurotus ostreatus), 표고(Lentinula edodes), 팽이(Flammulina velutipes)의 열풍건조 및 로스팅 시료를 대상으로 상온 (20-25 ̊C) 및 저온저장(4 ̊C) 3개월 후의 시료와 저장 전의 시료와의 항산화능, 아질산염 소거능 및 베타글루칸 성분 변화를 알아보기 위하여 실험을 수행하였다. DPPH 라디칼 소거능은 큰느타리와 표고의 열풍건조 시료를 제외하고 다른 열풍건조 및 로스팅 시료의 상온저장 처리가 가장 낮은 소거능을 나타냈다. 총 폴리페놀 함량은 큰느타리와 표고 열풍건조 시료를 제외하고 상온저장 시 함량치가 가장 낮았으며, 모든 식용 버섯류의 로스팅 시료에서 저장 전에 비하여 상온 및 저온저장 시에 함량이 감소하였다. 철환원 항산화능은 표고의 로스팅 시료를 제외하고 다른 버섯류의 열풍건조 및 로스팅 시료에서 저장 전에 비하여 상온 및 저온저장 시료에서 높아지는 경향이었으며, 환원력은 열풍건조 및 로스팅 시료의 상온 및 저온저장 시에 저장 전에 비하여 증가하는 경향을 나타냈다. 베타글루칸 함량의 경우, 열풍건조 및 로스팅 시료의 상온 저장된 시료에서 가장 낮은 함량치를 보였다. 본 연구의 결과는 식용버섯 가공원료의 상온 또는 저온저장 시에 버섯에 함유되어 있는 항산화, 베타글루칸 등과 같은 유용한 생리활성 성분의 변화 정도를 예측할 수 있는 기초적 자료로서 그 활용도가 높으리라 기대된다.

In this study, three kinds of bainitic steels are fabricated by controlling the contents of vanadium and boron. High vanadium steel has a lot of carbides and nitrides, and so, during the cooling process, acicular ferrite is well formed. Carbides and nitrides develop fine grains by inhibiting grain growth. As a result, the low temperature Charpy absorbed energy of high vanadium steel is higher than that of low vanadium steel. In boron added steel, boron segregates at the prior austenite grain boundary, so that acicular ferrite formation occurs well during the cooling process. However, the granular bainite packet size of the boron added steel is larger than that of high vanadium steel because boron cannot effectively suppress grain growth. Therefore, the low temperature Charpy absorbed energy of the boron added steel is lower than that of the low vanadium steel. HAZ (heat affected zone) microstructure formation affects not only vanadium and boron but also the prior austenite grain size. In the HAZ specimen having large prior austenite grain size, acicular ferrite is formed inside the austenite, and granular bainite, bainitic ferrite, and martensite are also formed in a complex, resulting in a mixed acicular ferrite region with a high volume fraction. On the other hand, in the HAZ specimen having small prior austenite grain size, the volume fraction of the mixed acicular ferrite region is low because granular bainite and bainitic ferrite are coarse due to the large number of prior austenite grain boundaries.

The oriental plum (Prunus salicina) is one of the most popular fruits in Korea due to its sweet taste and pleasant aroma. The objective of this study was to analyze the quality characteristics and antioxidant activities of a puree made using plums stored at low-temperatures. The quality characteristics were determined by estimating total soluble solids (TSS, °Brix), titratable acidity (TA, % citric acid), TSS/TA ratio, pH, colors, sugar content, and sensory profiles. The antioxidant effects were estimated by total polyphenol and flavonoid content and radical scavenging activity. The results showed that the plum puree containing both the flesh and the peel had markedly higher red coloration (a* value) than the puree without the peel, while yellow coloration (b* value) and lightness (L* value) were lower in the puree without the peel than with the peel. The sensory qualities including the plum taste and flavor, texture as well as overall acceptance showed no significant variation between the samples. Meanwhile, the total polyphenol/flavonoid content and radical scavenging activities were significantly improved by the presence of fruit peel and by frozen storage. These findings suggest that frozen plums could be a suitable ingredient for making a puree and concentrate for the food manufacturing industry.

Ammonium (NH4 +-N) and nitrate-nitrogen (NO3-N) fertilizers were spread 30 kg/10a and 60 kg/10a, respectively, as additional fertilizers in nitrogen fertilization to investigate their effects on spring kimchi cabbage's physiological disorders during cold storage. The initial weight of spring kimchi cabbage after harvesting was 3.80 kg with two-fold NO3-N, whereas it was 3.22 kg with one-fold NO3-N. After 90 days of cold storage, the total loss ratio became lower as the nitrogen fertilizer ratio increased. The pH increased, reducing sugar content decrease during the storage. Black speck occurrence became higher as the nitrogen fertilizer increased. Mid-rib brown stain and soft rot were observed slightly in kimchi cabbage regardless of the nitrogen fertilizer ratio. Two-fold NO3-N fertilization showed a positive effect on increasing weight and reducing kimchi cabbage loss, but it exhibited a negative effect on the black speck. The method and content of nitrogen fertilization of spring kimchi cabbage may be adjusted according to the usage and storage periods.

In this paper, the performance characteristics of a cryogenic refrigeration system used in fields such as HMR(Home Meal Replacement) that require ultra-low temperatures of -50℃ using natural refrigerants according to the recent enforcement of the Atmosphere Environment Conservation Act were investigated. For this purpose, a 2-stage compression refrigeration system using R744(CO2) and a cascade refrigeration system using R747/R404A and R747/R717(NH3) were applied. The COP(coefficients of performance) of each refrigeration system were compared according to changes in evaporation and condensation temperature, subcooled and superheated degree. Although the coefficient of performance of the 2-stage compression refrigeration system using R744 was superior to that of the cascade refrigeration system, 2-stage refrigeration system was considered that various problems should be solved in practical terms. In addition, the COP of R744/R717 for various operating conditions showed similar results to R744/R404A, so the possibility of alternativeness could be confirmed in the cascade refrigeration system.

As the International Maritime Organization (IMO)'s environmental regulations on ship emissions become strict, the demand for ships powered by Liquefied Natural Gas (LNG) is rapidly increasing worldwide. Compared to other materials, high manganese steel has the advantages of superior impact toughness at cryogenic temperatures, a small coefficient of thermal expansion, and low cost of base materials and welding rods. However, there is a limitation in that the mechanical properties of the filler material are lower than the base material having excellent mechanical properties. In this study, after performing a high manganese steel laser butt welding experiment, the welding performance was evaluated through mechanical property (yield strength, tensile strength, hardness, cryogenic impact strength) tests of the weld. As a result, it was observed that the yield strength and tensile strength of the high manganese steel laser welding part was 97.5% and 93.5% of the base metal respectively. Also the hardness of welding part was 84.2% of the base metal. The cryogenic impact strength of the welding part and the base metal were over the 27J, the level of welding part is 76.1% of the base metal.

LNG makes cryogenic conditions, so metals without low-temperature brittleness must be used. The International Maritime Organization (IMO) defines 9% Nickel steel, STS304L, 36% Nickel steel and Al5083 as metals that can be used in cryogenic conditions through the IGC Code. In this study, Al5083-O was studied to minimize welding distortion, and verified through finite element analysis and experiments. The block dumping method, which is advantageous in terms of analysis time and cost, was used, not the continuous heat source method. The constraint models with the thickness direction and the tensile force model were compared with the reference model, it was confirmed that the tensile force model had no significant effect. After verifying through the experiment, it was confirmed that the trend of the finite element analysis model was consistent with the experiment. Through this study, a welding distortion minimization model could be found with the block dumping method. It is judged that simulation of many models through short time analysis will be of great help in the field.

Natural gas is the most realistic fuel among eco-friendly fuels. Natural gas production is limited, and in Korea, it is supplied and utilized in the form of liquefied natural gas (LNG). In the case of LNG, the vaporization point is 163 degrees below zero, so ordinary metal cannot be used due to its brittleness. The International Maritime Organization (IMO) defines metals that can be used in the IGC Code, and is used for storage containers, transportation containers, etc. based on the metals. Welding is essential in the manufacture of large structures such as LNG storage tanks. In this study, weldability studies related to cryogenic materials were conducted. In Part I of this study, high-manganese steel and part II were studied for two types of stainless steel (STS304L, STS316L), and in Part III, aluminum (AL5083). During laser welding, the shape of the Bead on Plate (BOP) was analyzed, and a total of nine cases were analyzed using laser power and welding speed as variables. It was confirmed that the penetration and the width of the welding width were linearly proportional to the amount of heat input. Based on this study, it is possible to conduct a follow-up study to find the optimal welding conditions for butt welding and fillet welding.

As the part of efforts to respond to the environmental pollution, the demand for clean energy is increasing. Natural gas is one of the most realistic alternatives, and interest in the storage and transportation containers to utilize the natural gas is growing. The production area of ​​natural gas is limited, and in Korea, it is imported in the form of liquefied natural gas. LNG is a cryogenic state with a vaporization point of -163°C, so the ordinary metal cannot be used due to its brittleness. The international maritime organization (IMO) defines the metals that can handle LNG in the IGC Code, and the research is ongoing. This study was a preliminary study to check the weldability of related metals and confirmed the shape of bead on plate (BOP) during the laser welding for each material. In part I, a study was conducted on the high manganese steel, and in part II, a study was conducted on the materials of STS304L and STS316L among the stainless steel. Based on this study, it can be used as an optimal welding condition for the butt and fillet welding.

As demand for eco-friendly energy increases, demand for natural gas and Liquefied natural gas (LNG) storage technologies continues to increase. LNG is a cryogenic environment with a temperature of -163°C, so ordinary metals cannot be used due to brittleness. Accordingly, IGC Code designates the cryogenic materials such as Invar, STS304L, Al5083-0, and High Manganese Steel. For fabricating those materials, research on welding possibility is the most important. Thus this study focused on the possibility of laser welding of the cryogenic materials. The weldability of High Manganese Steel was researched in this paper, the shape and the dimensions of the beads after bead on plate (BOP) welding were observed. The experiment was conducted on a total of 25 cases with laser power and welding speed of 5 cases each, and the width, height, and penetration of the beads were confirmed. It was confirmed that the paramenter of bead increased linearly with the laser power, and the paramenters of bead increased linearly with decreasing welding speed. Based on this study, high manganese steel can be applied in various industries by applying it to butt welding.

Effect of 6kg large unit with the carton box (20% open ratio) and MA box (10,000cc·m-2·day-1·atm-1 oxygen transmission rates modified atmosphere package), and the 100g small unit with MA film on asparagus sensory quality were evaluated. The CO2 concentration depended largely on the packing unit and maintained at around 3% in small MA packages, whereas in the MA box increased to 12%. Ethylene concentration rapidly increased until after 3 days of storage in MA packages and then decreased to maintain 5μL·L-1. Unrelated to the unit size, the lower weight loss was obtained in MA packages. A significant difference in visual quality was shown since the 15th day, the best and worst were the MA box and small MA package on the finish day. Off-odor was the highest in small MA packages and the lowest in the carton box (< 3.0). Although there was no significant difference in firmness among all treatments, the packages showed the highest firmness in tips and stems, respectively. The sugar content and hue angle decreased during storage, but there was no statistical difference in all treatments. EL was lowest and highest in small MA package and carton box, respectively. On the 10th day, the total aerobic bacteria was lowest in small MA packages, but no significant difference on the 20th day. E. coli was not found in all treatments on the 10th day, while it was the lowest in the MA box on the 20th day. The mold and yeast were not observed during the whole storage. Based on the above results, the carton box packaged with 10,000cc OTR film was more effective in maintaining the quality of green asparagus with the suitable CO2 concentration for asparagus cold storage.